
Class , oJ % 



Book. 



,4 



ex 



GopyrigTrtN°_. 



*2 



COPYRIGHT DEPOSIT. 



Complete Examination 

Questions and Answers for 

Marine and Stationary Engineers 

A Complete Engine Operator's Catechism 

Giving the Latest and Most Approved Answers to all Leading Questions which 
will be Asked for the Purpose of Examining and Determining the Quali- 
fications of Applicants for Licenses for Engineers and for Persons 
having Charge of Steam Boilers as Approved by all Muni- 
cipalities and Government Boards of Examining 
Engineers, both Stationary and Marine 

Special Reference to Modern Types of Oil Engines 

BY 

CALVIN Fv SWINGLE, M.E. 

Author of "Twentieth Century Hand-Booh for Steam Engineers 
and Electricians,''' "Modem Locomotive Engineering 
Hand-Book," "Steam Boilers: Their Con- 
struction, Care and Operation" Etc. 



ILLUSTRATED 



CHICAGO 

FREDERICK J. DRAKE & CO. 

PUBLISHERS 



-T5 






1 



<=°l 



Copyright 1922, 1917, 1914 and 1906 

By 

Frederick J. Drake & Co. 



Printed in U. S. A. 



& 



fi 



< 



MmR 10 1922 



§)C!.A654901 



CONTENTS 

CHAPTER I 

PAGE 

Steam, Heat, Combustion and Fuels 7 

CHAPTER II 
The Boiler 25 

CHAPTER III 
Boiler Construction 65 

CHAPTER IV 
Boiler Settings and Appurtenances 81 

CHAPTER V 
Boiler Operation 128 

CHAPTER VI 
Types of Engines — Classification 173 

CHAPTER VII 
Condensers — Air- Pumps — Sea-Water 211 

CHAPTER VIII 
Auxiliary Machinery and Fittings 240 

CHAPTER IX 
The Indicator — Principles of the Indicator 270 

CHAPTER X 
The Steam Turbine — Fundamental Principles 304 

CHAPTER XI 
Modern Types of Oil Engines 361 



INTRODUCTION 



The development of the science of steam engineering 
and the continually increasing demand for more power 
for manufacturing purposes and for transportation, both 
on land and sea, have in these modern times resulted in 
the creation of power plants, which are truly marvelous 
in their details when compared with the steam machinery 
of forty years ago. Even the last twenty years have 
witnessed tremendous developments along these lines, and 
we may imagine the effect it would have upon an 
engineer, who twenty years ago was counted as first class 
in his business, but who, having taken a Rip Van Winkle 
sleep of twenty years, is suddenly awakened and finds him- 
self set down in the engine room of a first-class ocean 
steamer, or in the midst of one of our modern up-to-date 
power plants. The facts are, he would have hard work 
to recognize his surroundings. Even the steam gaugee 
would indicate a pressure of 150 to 175 pounds more per 
square inch than did the old-time gauges. Therefore, in 
view of the remarkable improvements in steam machinery 
which have been made and are continually being made, it 
certainly behooves engineers to do their utmost to keep 
step with the march of progress. The author has endeav- 
ored, in the following pages, to place before his readers 
information in a catechetical form which will be found to 
cover all of the various details appertaining to the opera- 
tion of modern steam plants, both stationary and marine. 

C. F. S. 



CHAPTER I 

STEAM, HEAT, COMBUSTION, AND FUELS 

Ques. 1. — What is steam? 

Ans. — Steam is vapor of water. 

Ques. 2. — At what temperature will water evaporate 
(boil) in the open air at sea level? 

Ans. — 212 degrees Fahrenheit. 

Ques. 3. — If 1 cubic foot of water is evaporated at 
212 degrees into steam at atmospheric pressure, how 
many cubic feet of steam will there be? In other words, 
what will the volume of the steam be? 

Ans. — 1,646 cubic feet. 

Ques. 4. — Then what is the relative volume of steam 
at atmospheric pressure, and the water from which it was 
evaporated at 212 degrees? 

Ans.— 1,646 to 1. 

Ques. 5. — What is the relative volume of steam at 
200 pounds gauge pressure, and the water from which it 
was generated? 

Ans.— 132 to 1. 

Ques. 6. — What is meant by the terms atmospheric 
pressure, gauge pressure, and absolute pressure, as 
applied to steam and other gases? 

Ans. — The pressure in pounds exerted by the steam, 
or gas, on each square inch of the interior surface of the 
containing vessel, tending to rupture it. 

7 



8 



QUESTIONS AND ANSWERS 



Ques. 7. — What is vacuum? 

Ans. — The absence of all pressure in the interior of a 
vessel. 

Table 1, which follows, shows the physical properties 
of saturated steam from a perfect vacuum up to 1,000 
pounds absolute pressure. It will be found convenient 
for reference. 



TABLE I 

Properties of Saturated Steam 



►> 


SI 




Total 


Heat 







s 


40 
O 


u 

o 


Absolute 

Pressure 

Lbs. per Sq. Inc 


J* 

P. CO 

Q 


above 


32 U F. 


latent Heat 

H-h 

Heat units 




> 

•S3 

"a; 


.5 

M 


O • 


So 
i> to 

u 

a 


In the Water 

h 

Heat-units 


In the Steam 

H 

Heat-units 


~ 


29.74 


089 


32. 


O. 


IO9I.7 


I09I.7 


208,080 


3333.3 


.0005 


29.67 


.122 


40. 


8. 


IO94. 1 


1086. 1 


154,330 


2472.2 


.0004 


2Q.56 


.176 


50. 


18. 


1097.2 


IO79.2 


107,630 


I 724. I 


.0006 


29.40 


.254 


60. 


28.01 


II00.2 


I072.2 


76,370 


1223.4 


.0008 


29.19 


•359 


7o. 


38.02 


1 103. 3 


1065.3 


54,660 


875.61 


.0011 


28.90 


.502 


80. 


48.04 


1106.3 


1058.3 


39,690 


63 s. So 


.0016 


28.51 


.692 


90. 


58.06 


110Q.4 


I05L3 


2Q,290 


469. 20 


.0021 


28.00 


•943 


100. 


68.08 


1112.4 


1044.4 


21,830 


34970 


.0028 


27.88 


I. 


102. 1 


70.09 


1113.1 


IO43.O 


20,623 


334.23 


.0030 


25.85 


2. 


126.3 


94.44 


1120.5 


I026.O 


10,730 


173.23 


.0058 


23.83 


3- 


141. 6 


109.9 


1125.1 


1015.3 


7,325 


118.00 


.0085 


21.78 


4. 


I53.I 


121. 4 


1128.6 


1007.2 


5,538 


89. So 


.0111 


19.74 


5. 


162.3 


130.7 


II3I-4 


1000. 7 


4,. c 30 


72.50 


.0137 


17.70 


6. 


1 70. 1 


138.6 


1133.8 


995-2 


3,8i6 


61.10 


.0163 


15.67 


7. 


176.9 


145.4 


II35.9 


990.5 


3.302 


53.00 


.0189 


13.63 


8. 


1S2.9 


I5I.5 


1137.7 


9S6.2 


2,912 


46.60 


.0214 


II.60 


9. 


188.3 


156.9 


H39-4 


982.4 


2,607 


41.82 


.0239 


9.56 


10. 


193.2 


161.9 


1140.9 


979.0 


2,361 


37.8o 


.0264 


7.52 


11. 


197.8 


166.5 


1142.3 


975.8 


2,159 


34.61 


.0289 


5-49 


12. 


202.0 


170.7 


II43.5 


972.8 


1,990 


31.90 


.0314 


3.45 


13. 


205.9 


174.7 


1 144. 7 


970.0 


1,846 


29.60 


.0338 


1.41 


14. 


209.6 


178.4 


II45.9 


967.4 


1,721 


27.50 


.0363 


o.OO 


14.7 


212.0 


180.9 


1 146. 6 


965.7 


1,646 


26.36 


.0379 



STEAM, HEAT, COMBUSTION, AND FUELS 

Table I — Continued 










Total Heat 




cu 


a 









p4 


Above 


32° F. 


■4-» 

d co 


S 






CO 6* 

0) ex 
be . 
a to 


cu o* 

£<? 

CU CU 
SO- 


0. CO 

a w 
fc CU 

Q 


« to 
rt .- 

*-? 

■a ? 


1 - 
re -4-» 

s -a 


4; ■*-» 

£ cu 

-1 * 


"0 

> 

cu 
> 
'■*■* 


5i 


U rt 


0"-5 


< 




+, cu 

a w 


; « 




psS 


t-i 

H 










t— < 


H-t 








O.3 


15 


213.3 


181. 9 


II46.9 


965.O 


1,614 


25.90 


.0387 


i-3 


16 


216.3 


185.3 


II47.9 


962.7 


1,519 


2403 


.0411 


2.3 


17 


219.4 


188.4 


II48.9 


96O.5 


1,434 


23.00 


.043? 


3.3 


18 


222.4 


191.4 


1 149. 8 


958.3 


1,359 


2I.80 


.0459 


4-3 


19 


225.2 


194.3 


1 1 50.6 


956.3 


1,292 


20.70 


.O483 


5-3 


20 


227.9 


i97.o 


II5I.5 


954-4 


1,231 


19.72 


.0507 


6.3 


21 


230.5 


199.7 


1152.2 


952.6 


1,176 


18.84 


.0531 


7-3 


22 


233.0 


202.2 


H53.0 


950.8 


1,126 


18.03 


.0555 


8.3 


23 


235.4 


204.7 


II53.7 


949.1 


1,080 


17.30 


.0578 


9-3 


24 


237.8 


207.0 


"54.5 


947.4 


1,038 


16.62 


.0602 


10.3 


25 


240.0 


209.3 


"55-1 


945.8 


998 


ID.OO 


.062 5 


".3 


26 


242.2 


211. 5 


"55.8 


944-3 


962 


15.42 


.O649 


12.3 


27 


244.3 


213.7 


1156.4 


942.8 


929 


I4.90 


.0672 


13.3 


28 


246.3 


215.7 


"57.1 


94L3 


898 


I4.40 


.0696 


14.3 


29 


248.3 


217.8 


"57-7 


939-9 


869 


13.91 


.0719 


15.3 


SO 


250.2 


219.7 


"58.3 


938.9 


841 


13.50 


.0742 


16.3 


31 


252.1 


221.6 


1158.8 


937-2 


816 


I3.07 


.0765 


17.3 


32 


254.0 


223.5 


"59-4 


935.9 


792 


12.68 


.0788 


18.3 


33 


255.7 


225.3 


"59-9 


934-6 


769 


12.32 


.0812 


19-3 


34 


257.5 


227.1 


1 160. 5 


933-4 


748 


12.00 


.0835 


20.3 


35 


259.2 


228.8 


1161.0 


932.2 


728 


11.66 


.O858 


21.3 


36 


260.8 


230.5 


1161.5 


931.0 


709 


11.36 


.088O 


22.3 


37 


262.5 


232.1 


1162.0 


929.8 


691 


11.07 


.O9O3 


23-3 


38 


264.0 


233.8 


1 162. 5 


928.7 


674 


10.80 


.0926 


24.3 


39 


265.6 


235.4 


1162.9 


927.6 


658 


10.53 


.0949 


25.3 


40 


267.1 


236.9 


1163.4 


926.5 


642 


10.28 


.0972 


26.3 


4i 


268.6 


238.^ 


1163.9 


925.4 


627 


10.05 


.0995 


27.3 


42 


270.1 


240.0 


1164.3 


924.4 


613 


9.83 


.IOI8 


28.3 


43 


271.5 


241.4 


1164.7 


923.3 


600 


9.61 


.1040 


29.3 


44 


272.9 


242.9 


1165.2 


922.3 


587 


9.41 


.IO63 


30.3 


45 


274.3 


244.3 


1165.6 


921.3 


575 


9.21 


.1086 


31.3 


46 


275.7 


245.7 


1166.0 


Q20.4 


563 


9.02 


.IIO8 


32.3 


47 


277.0 


247.0 


1 166. 4 


9I9.4 


552 


8.84 


.1131 


33-3 


48 


278.3 


248.4 


1166.8 


918.5 


541 


8.67 


."53 


34-3 


49 


279.6 


249.7 


1167.2 


917.5 


531 


8.50 


.1176 


35.3 


5o 


280.9 


251.0 


1167.6 


916.6 


520 


8-34 


.1198 


36.3 


51 


282.1 


252.2 


1168.0 


915.7 


5" 


8.19 


.1221 


37.3 


52 


283.3 


253.5 


1168.4 


914.9 


502 


8.04 


.1243 



10 



QUESTIONS AND ANSWERS 



Table i — Co?iti?i tied 



m cf 
C- u 

~ z. 
it . 

•Z 09 



38.3 

39-3 
40-3 
41.3 
42.3 
43 3 
44-3 
45-3 
46.3 
47-3 
48.3 
49-3 
50.3 
51.3 
52.3 
53 3 
54.3 
55.3 
56.3 
57.3 
53.3 
59-3 
60.3 
61.3 
62.3 
63.3 
64.3 
65.3 
66.3 

67.3 

68.3 

69.3 
70.3 

71-3 
72.3 

73-3 
74.3 
75-3 



3 a 

Irt 

< 



53 
54 
55 
56 
57 
58 

59 
60 
61 
62 
63 
64 
65 
66 

67 
68 
69 
70 

7i 

72 
73 
74 
75 
76 
77 
78 

79 
80 

81 
82 
83 
84 
85 
86 

87 

88 

89 
90 



c ■ 
c o 

Hg 

Q 



284.5 
285.7 
286.9 
288.1 
289.1 
290.3 
291.4 
292.5 
293.6 
294-7 
295.7 
296.8 
297.8 
293. S 
299.8 
300. s 

301.8 
302.7 
303.7 
304.6 
305.6 
306.5 
307.4 

308.3 
309.2 

3 10. 1 
310.9 
311. 8 
312.7 
313.5 
3U4 
315.2 
316.0 
316.8 
317.7 
3IS.5 
319.3 
320.0 



Total Heat 
above 32 F. 






254-7 
256.0 
257.2 
253.3 
259.5 
260.7 
261.8 
262.9 
264.0 
265.1 
266.2 
267.2 
26S.3 
269.3 
270.4 

271.4 
272.4 
273.4 
2 74-4 
275.3 
276.3 
277.2 
27S.2 
279.1 
2S0.0 
2S0.9 

2S2.7 
2S3.6 
2S4.5 
2S5.3 
2S6.2 
2S7.0 

2S7.9 
288.7 
2S9.5 
290.4 
291.2 



5 2 



168.7 
169. 1 
169.4 
169.8 

170. 1 

170.5 
170.S 

171. 2 

171. 5 

171. S 
172. 1 
172.4 
172.8 
173- 1 
173-4 
173-7 
174.0 
174-3 
174-6 
174.8 
175. 1 
175-4 
175-7 
176.0 
176.2 
176.5 
176.S 
177.0 

177.3 
177.6 

177.S 
173. 1 
178.3 

178.6 
178.8 
1 79- 1 
179.3 
179.6 



-r - 



914.0 


492 


913-1 


484 


912.3 


476 


911.5 


46S 


910.6 


460 


909.3 


453 


909.0 


446 


903.2 


439 


Q07.5 


432 


906.7 


425 


905.9 


419 


005.2 


413 


904.5 


407 


903.7 


401 


903.0 


395 


902.3 


390 


901.6 


3S4 


000.9 


379 


900.2 


374 


899-5 


369 


89S.9 


365 


89^.2 


360 


897.5 


356 


896.9 


351 


S96.2 


347 


895.6 


343 


895.0 


339 


394.3 


334 


893.7 


331 


893.1 


327 


892.5 


323 


891.9 


320 


891.3 


316 


890.7 


313 


890.1 


309 


889.5 


306 


8S8.9 


303 


8S8.4 


299 



5* 



7.90 
7.76 
7.63 
7.50 
7.38 
7.26 

7.14 
7.03 
6.92 
6.S2 
6.72 
6.62 
6.53 
6.43 
6.34 

6.2> 

6 

6 

6 



17 
09 
01 

93 

5.S5 

7i 
63 

57 
50 

5-43 
5-37 
5.31 
5.25 
5.iS 

513 

5.07 
5.02 
4.96 
4.91 
4.36 
4.S1 



STEAM, heat;, combustion, and fuels 
Table i — Continued 



11 





a 




Total Heat 




CD 


5 


•** 



fid 

53 »h 


=3 d 

cm— 1 
en 


a 4> 


above 


32 F. 


a en 


E 

3 


- * 


. 


CO • 

to a* 

Cu >- 


cu <u 


u 

<D en 


"S 


ffi '3 
sit: 


"0 
> 




-D - 


v P. 
be . 

S3 CO 

Oj-O 


" 4 " > Cl 

cojo 


Q 


j3 (Z 




•3 ffi 


*cd 




M & 


CM 


^ 




H-t 

d ►* 

t-H 


a as 




g 




76.3 


91 


320.8 


292.0 


1179.8 


887.8 


296 


4.76 


.2102 


77.3 


92 


321.6 


292.8 


1 180.0 


887.2 


293 


4.71 


.2123 


78.3 


93 


322.4 


293.6 


1180.3 


886.7 


20>0 


4-66 


.2145 


79-3 


94 


323.1 


294.4 


1180.5 


886.1 


287 


4.62 


.2166 


80.3 


95 


323.9 


295.1 


1180.7 


885.6 


285 


4.57 


.2188 


81.3 


96 


324.6 


295.9 


1181.0 


885.0 


282 


4.53 


.2210 


82.3 


97 


325.4 


296.7 


1181.2 


884.5 


279 


4.48 


.2231 


83.3 


98 


326.1 


297.4 


1181.4 


884.0 


276 


4-44 


.2253 


84.3 


99 


326.8 


298.2 


1181.6 


883.4 


274 


4.40 


.2274 


85.3 


100 


327.6 


298.9 


1181.8 


882.9 


271 


4.36 


.2296 


86.3 


IOI 


328.3 


299.7 


1182.1 


882.4 


268 


4.32 


.2317 


87.3 


102 


329.0 


300.4 


1182.3 


881.9 


266 


4.28 


.2339 


88.3 


103 


329.7 


30I. I 


1182.5 


881.4 


264 


4.24 


.2360 


89.3 


104 


330.4 


30I.9 


1182.7 


880.8 


26l 


4.20 


.2382 


90-3 


105 


33i. 1 


302.6 


1182.9 


880.3 


259 


4.16 


.2403 


9!-3 


106 


331.8 


303.3 


1183.1 


879.8 


257 


4.12 


.2425 


92.3 


107 


332.5 


304.0 


1183.4 


879.3 


254 


4.09 


.2446 


93.3 


108 


333-2 


304.7 


1183.6 


878.8 


252 


4.05 


.2467 


94-3 


109 


333-9 


305.4 


1183.8 


878.3 


250 


4.02 


.2489 


95.3 


no 


334.5 


306.1 


1184.0 


877.9 


248 


3.98 


.2510 


96.3 


III 


335-2 


306.8 


1184.2 


877.4 


246 


3.95 


.2531 


97.3 


112 


335-9 


307.5 


1 1 84.4 


876,9 


244 


3.92 


.2553 


98.3 


113 


336.5 


308.2 


1184.6 


876.4 


242 


3.88 


.2574 


99-3 


114 


337.2 


308.8 


1184.8 


875.9 


24O 


3.85 


.2596 


100.3 


115 


337.8 


309.^ 


1185.0 


875.5 


238 


3.82 


.2617 


101.3 


Il6 


338.5 


310.2 


1185.2 


875.0 


236 


3-79 


.2638 


I02.3 


117 


339-1 


3I0.8 


1185.4 


874.5 


234 


3.76 


.2660 


103.3 


Il8 


339-7 


311. 5 


1185.6 


874.1 


232 


3-73 


.2681 


104.3 


119 


340.4 


312.1 


1185.8 


873.6 


230 


3-70 


.2703 


105.3 


120 


341.0 


312.8 


1185.9 


873.2 


228 


3.67 


.2764 


106.3 


121 


341.6 


313.4 


1 186. 1 


872.7 


227 


3-64 


.2745 


107.3 


122 


342.2 


314. 1 


1186.3 


872.3 


225 


3.62 


.2766 


108.3 


123 


342.9 


314.7 


1186.5 


871.8 


223 


3-59 


.2788 


109.3 


124 


343.5 


315.3 


1186.7 


871.4 


221 


3.56 


.2809 


no. 3 


125 


344.1 


316.0 


1186.9 


870.9 


220 


3.53 


.2830 


in. 3 


120 


344-7 


316.6 


1187.1 


870.5 


218 


3.51 


2851 


112.3 


127 


345-3 


317.2 


1187.3 


870.0 


216 


3.48 


.2872 


«3.3 


128 


345-9 


317.8 


1187.4 


869.0 


215 


3.46 


.2894 



12 



QUESTIONS AND ANSWERS 



Table i — Continued 










Total Heat 




CD 


S 






2d 


9d 

CO>— » 

co . 


1x1 


Above 


32° F. 


rt co 


£ 


c a) 


fct, CO 


S o 1 


*3 


rv to 
E <U 


u 

« CO 

^2 ■*-» 


1 - 

CO w 


tHe 

-h 
-unit 


'o 

> 




XI - 


<u 


V <u 


D »- 


ct — 1 


<u .— 




O 




(J a 




3 


hS 


*-S 




£^3 


> 


s? 


•"• 4-1 


3 CO 




Q 






2 x 


«i 


5d 




OJ 


<^ 




^3 <u 






& 


• O 


"4-3 


129 


346.5 


318.4 


1187.6 


869.2 


213 


3-43 


.2915 


JH5.3 


I3O 


347-1 


3I9.I 


1187.8 


868.7 


212 


3.41 


.2936 


116.3 


131 


347.6 


319.7 


1188.0 


868.3 


210 


3.38 


.2957 


117.3 


132 


348.2 


320.3 


1188.2 


867.9 


209 


3-36 


.2978 


118.3 


133 


348.8 


320.8 


IIS8.3 


867.5 


207 


3-33 


.3000 


119.3 


134 


349-4 


321.5 


H38.5 


867.0 


206 


3.31 


.3021 


120.3 


135 


350.0 


322.1 


1188.7 


866.6 


204 


3.29 


.3042 


121. 3 


I36 


350.5 


322.6 


1188.9 


866.2 


203 


3.27 


.3063 


122.3 


137 


35i. 1 


323.2 


1189.0 


865.8 


201 


3.24 


.30S4 


123.3 


138 


351.8 


323.8 


1189.2 


865.4 


200 


3.22 


.3105 


124-3 


139 


352.2 


324.4 


1 189.4 


865.0 


199 


320 


.3126 


125.3 


I4O 


352.8 


325.0 


1189.5 


864.6 


197 


3.18 


•3147 


126 3 


141 


353.3 


325.5 


1189.7 


864.2 


196 


3.16 


.3169 


127.3 


142 


353-9 


326.1 


1189.9 


863.8 


195 


3.14 


.3190 


128.3 


143 


354-4 


326.7 


1190.0 


863.4 


193 


3- 11 


.3211 


129.3 


144 


355.o 


327.2 


1190.2 


863.0 


192 


3.09 


.3232 


130.3 


145 


355.5 


327.8 


1190.4 


862.6 


191 


3.07 


.3253 


1313 


I46 


356.0 


328.4 


1190.5 


862.2 


190 


3-05 


.3274 


T33-3 


148 


357.1 


329.5 


1190.9 


861.4 


187 


3.02 


.3316 


135.3 


I50 


358.2 


330.6 


1191.2 


860.6 


1S5 


2.98 


.3358 


M0.3 


155 


360.7 


333.2 


1192.0 


858.7 


179 


2.89 


.3463 


145.3 


l60 


363.3 


335.9 


1192.7 


856.9 


174 


2. So 


.3567 


150.3 


165 


365.7 


338.4 


II93.5 


855.1 


169 


2.72 


.3671 


155.3 


170 


368.2 


340.9 


1194.2 


853.3 


164 


2.65 


•3775 


160.3 


175 


370.5 


343.4 


1 194.9 


851.6 


160 


2.58 


.3879 


165.3 


l80 


372.8 


345.8 


1195.7 


849.9 


156 


2.51 


.3983 


170.3 


185 


375.1 


348.1 


1106.3 


848.2 


152 


2.45 


.4087 


175.3 


I9O 


377-3 


350.4 


1197.0 


846.6 


148 


2.39 


.4191 


180.3 


195 


379.5 


352.7 


1197.7 


845.0 


144 


2.33 


.4296 


185.3 


200 


381.6 


354-9 


1198.3 


843.4 


141 


2.27 


.4400 


190.3 


205 


383.7 


357-1 


1 199.0 


841.9 


138 


2.22 


.4503 


1953 


2IO 


385.7 


359.2 


1199.6 


840.4 


135 


2.17 


.4605 


200.3 


215 


387.7 


361.3 


1200.2 


838.9 


132 


2.12 


.4707 


205.3 


220 


389.7 


362.2 


1200.8 


838.6 


129 


2.06 


.4^2 


245.3 


26o 


404.4 


377-4 


1205.3 


827.9 


no 


1.76 


.5686 


285.3 


300 


417.4 


390.9 


1209.2 


818.3 


06 


1-53 


.6515 


485.3 


500 


467.4 


443.5 


1224.5 


781.0 


59 


•94 


1.062 


685.3 


700 


504.1 


482.4 


1235.7 


753.3 


42 


.68 


1.470 


9853 


IOOO 


546.8 


528.3 


1248.7 


720.3 


30 


.48 


2.082 



STEAM, HEAT, COMBUSTION, AND FUELS 1& 

Ques. 8. — How much pressure does the atmosphere 
exert upon the surface of the earth? 

Ans. — 14.7 pounds upon each square inch of the 
earth's surface. 

Ques. 9. — What is understood by gauge pressure? 

Ans. — Gauge pressure is the pressure over and above 
the 14.7 pounds atmospheric pressure. 

Ques. 10. — What is absolute pressure? 

Ans. — Absolute pressure is the total pressure above a 
perfect vacuum. It equals the sum of the gauge pressure 
and the atmospheric pressure. 

Ques. 11. — How does pressure influence the boiling 
point of water? 

Ans. — The higher the pressure, the higher must the 
temperature of the water be raised in order to cause it to 
boil. 

Ques. 12. — In what way does pressure affect the vol- 
ume of steam? 

Ans. — The higher the pressure, the smaller will be the 
volume of the steam generated from a given weight of 
water. 

Ques. 13. — In what light should steam be considered 
relative to work? 

Ans. — As an agent through which heat performs the 
work. 

Ques. 14. — What is the most important property of 
steam? 

Ans. — Its expansive force. • 

Ques. 15. — What law governs this expansion? 

Ans. — Boyle's law of expanding gases. 



14 QUESTIONS AND ANSWERS 

Ques. 16. — Define Boyle's law. 

Ans. — The volume of all elastic gases is inversely pro- 
portional tc their pressure. 

Ques. 17.— What is heat? 

Ans. — Heat is a form of energy which may be applied 
to or taken away from bodies. 

Ques. 18. — Name the original source of heat, at least 
for this planet. 

Ans. — The sun. 

Ques. 19. — How was this heat made available for 
man's use? 

Ans. — By being stored up in cil, wood, and the coal 
formations millions of years ago, by the rays of the sua, 

Ques. 20. — What is the relation of heat to matter? 

Ans. — All matter is charged with heat in a greater or 
less degree, depending upon the nature of the matter. 

Ques. 21. — What is the specific heat of any substance? 

Ans. — The ratio of the quantity of heat required to 

e a given weight of that substance 1 degree in temper- 
re, to the quantity of heat required to raise the same 
weight of water 1 degree in temperature, the water being 
at its maximum density, 39.1 degrees. 

The following table gives the specific heat of different 
substances in which engineers are most generally inter- 
ested: 

Table Xo. 2 

Water at 39.1 degrees Fahrenheit 1.000 

Ice at 32 degrees Fahrenheit 504 

Steam at 212 degrees Fahrenheit 480 

Mercury 033 

Cast iron , , 130 



STEAM, HEAT, COMBUSTION, AND FUELS 15 

Table No. 2 — Continued 

Wrought iron 113 

Soft steel 116 

Copper 095 

Lead 031 

Coal 240 

Air 238 

Hydrogen 3.404 

Oxygen 218 

Nitrogen 244 

Ques. 22. — What is sensible heat? 

Ans. — Heat imparted to a body, and warming it. 
Sensible heat in any substance can be measured in degrees 
of a thermometer. 

Ques. 23.— What is latent heat? 

Ans. — Heat given to a body and not warming it; that 
is, the heat that is not shown by the thermometer. 

Ques. 24. — Is the heat lost that thus becomes latent? 

Ans. — It is not. On the contrary, it was required to 
produce the change in the body from the solid to liquid, 
or from the liquid to the gaseous state. For instance, in 
the transformation of ice into water, 180 degrees of heat 
becomes latent, and in changing the water into steam at 
atmospheric pressure 965.7 degrees of heat become 
latent. 

Ques. 25. — What is the first law of thermo-dyna- 
mics? 

Ans. — Heat and work are mutually convertible; that 
is, a certain amount of work will produce a certain 
amount of heat, and the heat thus produced will, by its 
disapoearance, if rightly applied, produce a fixed amount 
vi rnecnanical energy. 



16 QUESTIONS AND ANSWERS 

Ques. 26. — How is heat measured with relation to 
work? 

Ans. — By the thermal unit. 

Ques. 27. — What is a thermal unit? 

Ans. — It is the quantity of heat required to raise ths 
temperature of one pound of pure water one degree, or 
from 39 degrees, its temperature of greatest density, to 
40 degrees. 

Ques. 28. — What is the mechanical equivalent of 
heat? 

Ans. — The mechanical equivalent of heat is the 
energy required to raise a weight of 778 pounds one foot 
high, or a weight of one pound 778 feet high; in other 
words, 778 foot pounds. This amount of energy is stored 
in one thermal unit, or heat unit. 

Ques. 29. — In how many ways is heat transmitted? 

Ans. — In two ways: — First by conduction; second, by 
radiation. 

Ques. 30. — What is conduction of heat? 

Ans. — Conduction is the transmission of heat from 
one body to another in direct contact with it. 

Ques. 31. — Are all bodies equally good conductors of 
heat? 

Ans. — No. The best conductors of heat are the 
metals, silver, copper, tin, steel, lead. The poorest 
conductors, or nonconductors, as they are termed, are 
hair, wool, straw, wood, liquids, and "dead" air, that is, 
air not in circulation. 

Ques. 32. — What is radiation of heat? 

Ans. — Radiation is the transmission of heat from one 



STEAM, HEAT, COMBUSTION, AND FUELS 17 

body to another through an intervening space between 
the bodies. 

Ques. 33. — How is the heat in the furnace or fire-box 
of a boiler transmitted to the water in the boiler? 

Ans. — By radiation and conduction through the heat- 
ing surface of the boiler. 

Ques. 34. — What is combustion? 

Ans. — Combustion is the chemical union of the carbon 
and hydrogen of the fuel with the oxygen of the air. 

Ques. 35. — What is one of the main factors in the 
proper combustion of fuels, especially coal? 

Ans.— A proper supply of air. 

Qu<?s. 36. — What is the principal constituent of coal, 
oil, and most other fuels? 

AnSo — Free or fixed carbon. 

Ques. 37. — Are there other combustibles in fuels? 

Ans. — Yes; hydrocarbons, a chemical combination of 
carbon and hydrogen in different ratios. 

Ques. 38. — State the composition of air. 

Ans. — By volume, 21 parts oxygen and 79 parts 
nitrogen; by weight, 23 parts oxygen and 77 parts 
nitrogen. 

Ques. 39. — In what proportion do the atoms of carbon 
and hydrocarbons combine with the atoms of oxygen to 
form perfect combustion? 

Ans. — One atom of carbon combines with two atoms 
of oxygen, expressed by the chemical symbol CO 2 . 

Ques. 40. — In the process of combustion, which com- 
bustible burns first? 

Ans. — When fresh fuel is added to the fire, the hydro- 



18 QUESTIONS AND ANSWERS 

carbons distill in the form of gas, and if the conditions 
of draught, admission of air, etc., are right, this gas will 
ignite and burn during its passage through the furnace 
and combustion chamber; otherwise it passes out of the 
stack in the form of smoke. 

Ques. 41. — What are the common products of com- 
bustion? 

Ans. — First, carbonic acid, resultant from the 
chemical union of one atom of carbon with two atoms of 
oxygen (symbol CO 2 ); second, water vapor, resultant 
from the chemical union of two portions of hydrogen, and 
one portion of oxygen (symbol H 2 0); third, inert gases, 
like nitrogen, also unassociated oxygen, ash, and other 
products, due to the impurities contained in the coal, or 
other fuel. 

Ques. 42. — In what form does the fixed carbon appear 
during the process of combustion? 

Ans. — After the hydrocarbons have left it, the fixed 
carbon appears in the form of a glowing mass of coke, 
uniting with the oxygen to form carbonic acid, and all 
the heat stored in the carbon is liberated, provided the 
supply of air is correct; otherwise carbon monoxide 
(symbol CO) is formed, and only about one-third of the 
stored heat is liberated, the larger portion of the carbon 
passing off in the form of soot and smoke. 

Ques. 43. — How many thermal units are contained in 
one pound of carbon? 

Ans. — 14,500 thermal units. 

Ques. 44. — Theoretically, how much air is required 
lor the complete combustion of one pound of coal? 



STEAM, HEAT, COMBUSTION, AND FUELb 19 

Ans. — By weight, 12 pounds; by volume, 150 cubic feet. 

Ques. 45. — Is this law carried out in practice? 

Ans. — It is not; a much larger quantity of air (20 to 
24 pounds per pound of coal) being supplied in order to 
; nsure that all the atoms of carbon may find oxygen. 

Ques. 46. — In what two ways is the air supplied to 
boiler furnaces? 

Ans. — First, by natural draught; second, by artificial 
or forced draught. 

Ques. 47. — What causes natural draught? 

Ans. — The air in the furnace and uptake becomes 
heated and consequently much lighter in weight than an 
equal column of outside air. The heated air is therefore 
continually rising and passing out of the funnel or smoke- 
stack, while the outside air rushes into the ash-pit and 
up through the grates to replace it. 

Ques. 48. — How many systems of artificial or forced 
draught are there? 

Ans. — There are two principal systems: First, that 
in which the air is forced directly into the ash-pits, 
through conduits leading directly from the fan, or other 
source of the blast; second, that in which the air is forced 
directly into the fire-room or stoke-hole, which is made 
air-tight for this purpose, and from thence the air finds 
its way into the furnaces on the same principle as when 
natural draught is employed. 

Ques. 49. — Mention the two most important factors 
in the regulation of combustion. 

Ans. — First, the draught; second, the kind and 
quality of the fuel. 



20 QUESTIONS AND ANSWERS 

Ques. 50. — What is meant by the expression "rate of 
combustion?" 

Ans. — The rate of combustion means the number of 
pounds of fuel burned per square foot of grate surface 
per hour. 

Ques. 51. — What are the usual rates of combustion 
with natural draught? 

Ans. — For stationary boilers with shaking grates, 
from 12 to 18 pounds of coal per hour; for marine 
boilers, from 15 to 25 pounds. 

Ques. 52. — What are the rates of combustion with 
artificial or forced draught? 

Ans. — For stationary boilers, 25 to 35 pounds; for 
marine boilers, 20 to 50 pounds. 

Ques. 53. — How should the air-supply be regulated in 
order to bring about complete combustion? 

Ans. — Complete combustion can be secured only when 
the air is brought into direct contact, not only with the 
fuel, but also with the gases as they develop. If the air 
passing into the furnace above the fuel is first heated, 
much better results can be attained. 

Ques. 54. — Why is it desirable to admit air (heated if 
possible) above the fire? 

Ans. — In order to supply to the hydrocarbons the 
oxygen necessary to their complete combustion. 

Ques. 55. — What will be the result if the supply of 
oxygen above the fire is not sufficient? 

Ans. — A portion of the hydrocarbons will pass off 
unburned, and of other portions, only the hydrogen is 
burned, leaving the carbon to pass off as soot or smoke. 



STEAM, HEAT, COMBUSTION, AND FUELS 21 

Ques. 56. — State another reason why the air should be 
admitted above the fire. 

Ans. — If carbon monoxide (CO) has been formed in 
the combustion of the fixed carbon, the air above the fir* 
would burn this into carbonic acid, thereby liberating i 
large additional amount of heat. 

Ques. 57. — What is indicated by the formation o) 
much smoke and soot? 

Ans. — Incomplete combustion, as smoke and soot are 
simply unoxydized particles of carbon. 

Ques. 58. — Is a high furnace temperature conducive 
to good combustion? 

Ans. — It is; because the hydrocarbons unite with the 
oxygen much more quickly, and the fixed carbon also is 
much more completely united with oxygen in a high 
temperature. 

Ques. 59. — Mention a very efficient agency for main- 
taining a high furnace temperature. 

Ans. — Fire-brick arches and baffiers, for the gases to 
impinge against. 

Ques. 60. — Assuming that good combustion is taking 
place in the boiler furnace, what will be the furnace tem- 
perature? 
_ Ans.— From 2,500 to 3,000 degrees Fahrenheit. 

Ques. 61. — What are the fuels most commonly used 
in boiler furnaces? 

Ans. — Coal, wood, and oil. 

Ques. 62. — What per cent of volatile matter is con- 
tained in most of the coals used in the marine service? 

Ans. — About 20 per cent. 



22 QUESTIONS AND ANSWERS 

Ques. 63. — What are the advantages of fuel oil? 
Ans. — Greater evaporative power for same weight and 
bulk, ease of manipulation, perfect control of the com- 
bustion to suit requirements of service, and cleanliness. 

Ques. 64. — What are the principal objections to the 
use of oil as fuel for boilers? 

Ans. — First, certain dangers involved in storing and 
using it; second, limited supply. 

Ques. 65. — State the difference between the heating 

value of a pound of bituminous coal and a pound of wood. 

Ans. — One pound of coal will evaporate from 8 to 

9 pounds of water; one pound of wood will evaporate 

from 2/^ to 3^2 pounds of water. 

Ques. 66. — What are the two principal kinds of coal 
used as fuel for boilers? 

Ans. — First, anthracite or hard coal; second, bitumin- 
ous or soft coal. 

Ques. 67. — State the composition of hard coal. 

Ans. — *Carbon per cent 91.05 

Volatile matter 3.45 

Moisture 1.34 

Ash M 4.16 

100.00 
Ques. 68. — State the composition of the best soft coals. 

Ans. — fFixed carbon per cent 75.02 

Volatile matter 20.34 

Moisture .61 

Ash M 3.47 

Sulphur .56 

100.00 

— Li i 

•Thurston. TKent. 



STEAM, HEAT, COMBUSTION, AND FUELS 



23 



Ques. 69. — Does this analysis apply to all bituminous 
coals? 

Ans. — No; some of the poorer kinds run as low as 40 
per cent in carbon, 32 per cent in hydrocarbons, and 12 
per cent in ash. 

Ques. 70. — How do these impurities affect the value 
of coal as a fuel? 

Ans. — The mineral combination of sulphur and iron 
affects the keeping qualities of some coals. Ashes and 
mineral substances form clinkers on the grate bars by 
fusing together, thereby greatly impeding the passage of 
air through the fire. 

Table No. 3 
Analysis of Coal from Different States. 



State 


Kind of Coal 


Moist- 
ure 


Vola- 
tile 
Matter 


Fixed 
Carbon 


Ash 


Sul- 
phuar 


Pennsylvania 


Youghiogheny 


1.03 


36.49 


59.05 


2.6l 


0.81 


4( 


Connellsville 


1.26 


30.IO 


59.61 


8.23 


0.78 


West Virginia 


Quinimont 


0.76 


18.65 


79.26 


1. 1 1 


0.23 


< < 


Fire Creek 


0.61 


22.34 


75.02 


1.47 


0.56 


E. Kentucky 


Peach Orchard 


4.60 


35.70 


53.28 


6.42 


1.08 


•< 


Pike County 


1.80 


26.80 


67.60 


3.8o 


o.97 


Alabama 


Cahaba 


1.C6 


33.28 


63.04 


2.02 


o.53 


•i 


Pratt Co.'s 


1.47 


32.29 


59.50 


6.73 


1.22 


Ohio 


Hocking Valley 


6.59 


35-77 


49.64 


8.00 


1.59 


it 


Muskingum " 


3.47 


37-83 


53-30 


5.35 


2.24 


Indiana 


Block 


8.50 


31.00 


57.50 


3.00 




i < 


<« 


2.50 


44-75 


51.25 


<l. 50 




W. Kentucky 


Nolin River 


4.7o 


33.24 


54.94 


fi.70 


2-54 


4 < 


Ohio County 


3.70 


30.70 


45.OO 


3.16 


I.24 


Illinois 


Big Muddy 


6.40 


30.60 


54.60 


8.30 


I.50 


«< 


Wilmington 


15.50 


32.80 


39.90 


II.80 




M 


11 screenings 


14.00 


28.00 


34.20 


23.80 




•1 


Duquoin 


8.90 


23.50 


60.60 


7.00 





Ques. 71. — How is coal measured? 

Ans. — Usually fc* weight in pounds or tons. For 
storage purposes between 42 and 44 cubic feet per ton of 
2,240 pounds are avowed. 



24 QUESTIONS AND ANSWERS 

Ques. 72. — What is the heating value in thermal units 
of one pound of bituminous coal? 

Ans. — 12,000 to 14,500 thermal units, depending upon 
the quality of the coal. 

Ques. 73. — What is the average composition of wood? 

Ans. — About 50 per cent of carbon, 40 per cent of 
oxygen, some hydrogen, and about 1 per cent of ash. 

Ques. 74. — What is the average heating value of 
wood expressed in thermal units? 

Ans. — From 6,000 to 8,000 thermal units per pound. 

Ques. 75. — What woods are generally used for fuel? 

Ans. — Hickory, oak, beech, pines, and firs. 

Ques. 76.— What are the principal disadvantages in 
the use of wood as a fuel for steam boilers? 

Ans. — First, a limited supply; second, great bulk in 
comparison to its heating value. 

Ques. 77. — State the composition of fuel oil. 

Ans. — Fuel oil contains about 86 per cent of carbon, 
13 per cent of hydrogen, and 1 per cent of oxygen. 

Ques. 78. — What is the heating value of fuel oil? 

Ans.— 20,000 to 22,000 thermal units per pound of oil. 

Ques. 79. — What are the relative heating values of 
coal and wood? 

Ans. — One pound of coal is equal to 2j/i pounds of 
wood. 

Ques. 80. — What is the best all-around fuel, with high 
heating value, and at reasonable cost? 

An*. — Coal. It is easily obtainable very nearly every- 
where; it is safe to handle, and has small bulk in propor- 
tion to its heating value. 



CHAPTER II 

THE BOILER. 

Ques. 81. — What are the leading types of boilers in 
use at the present day in the stationary and marine 
service? 

Ans. — First, fire-tube boilers; second, water-tube 
boilers. 

Ques. 82. — In what respect do they differ? 

Ans. — Fire-tube boilers have the hot gases inside the 
tubes and the water surrounding them, while in water- 
tube boilers the water is inside the tubes and the hot gases 
and flame are on the outside. 

Ques. 83. — Are boilers classified in any other way? 

Ans. — Yes; low-pressure boilers, in which 55 to 60 
pounds is the limit, and high-pressure boilers, carrying 
from 150 to 300 pounds pressure. 

Ques. 84. — What are the most common forms of fire- 
tube boilers? 

Ans. — First, the horizontal tubular boiler; second, 
the vertical tubular boiler; third, the Scotch boiler; 
fourth, the flue and return tube boiler; fifth, the Western 
river boiler. 

Ques. 85. — Describe the horizontal tubular boiler. 

Ans. — It consists of a cylindrical shell, having tubes 
of from 2 to 4 inches in diameter extending from head 
to head. There is usually a dome on top, and the 
boiler is set in brickwork, having the furnace underneath. 
The heated gases pass first under the boiler, and then 

25 



26 QUESTIONS AND ANSWERS 

return through the tubes to the breeching or uptake 
leading to the stack. 

Ques. 86. — What are the leading features of the verti- 
cal tubular boiler? 

Ans. — A cylindrical shell, having the fire-box or fur- 
nace in its lower end. The bottom ends of the tubes are 
expanded into the tube-sheet of the fire-box, and the top 
ends of the tubes are expanded into the top head of the 
boiler, and conduct the gases directly to the stack. 

Ques. 87. — Are the tubes entirely submerged in this 
class of boilers? 

Ans. — Not in all cases. Some forms of vertical boilers 
have a submerging chamber above the upper tube-sheet. 
This allows of a steam space above the top ends of the 
tubes, surrounding the smoke uptake, or smoke flue lead- 
ing to the stack. The tubes are thus entirely submerged. 
In the flush-tube boiler the steam and water space is below 
the upper tube-sheet or head of the boiler, thus leaving 
the upper portion of the tubes surrounded only by steam. 

Ques. 88. — Describe the Scotch boiler. 

Ans. — The Scotch boiler may be made either single- 
ended or double-ended. The shell is cylindrical, with 
flat heads. The diameters range from 10 to 15 feet, and 
in some cases even 20 feet, with a length of from 7 to 11 
feet. The Scotch boiler is horizontal, and is provided 
with two or more large corrugated furnace flues, placed 
near the bottom of the boiler, and extending from the 
front head to the combustion chamber in the rear. 

Ques. 89 — What is the diameter of these corrugated 
flues? 



THE BOILER 



27 



Ans.— From Z 1 /* to 4>4 feet, depen ng upon the size 
>f the boiler. 

Ques. 90.— How ar? these furnace flues secured in 

:he boiler? 




4 

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o 

OS 



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5 



A ns# — One end of the flue is riveted into the front 

^ead of the boiler, and the back end of the flue is rivetf 1 



28 



QUESTIONS AND ANSWERS 



Ques. 91. — Describe the combustion chamber of th< 
Scotch boiler. 

Ans. — It is a chamber built of steel boiler plate 
located at the rear end of the boiler, and entirely sur 
rounded by water. A nest of tubes extends from th< 
front sheet of the combustion chamber, above the cor- 
rugated furnace flue, to the front head of the shell. 




Fig. 2. Standard Horizontal Boiler with Full-arch Front Setting. 

Ques. 92. — Describe the course of the heated gases ii 
the Scotch boiler. 

Ans. — The furnaces proper, are placed within the cor 
rugated flues, near the front end. The gases and smoke 
pass through the flues to the combustion chamber, anc 
from thence return through the small tubes to the smoke 
box in front, and from there out through the stack. 

Ques. 93. — How are the flat sides of the combustion 
chamber staved? 



THE BOILER 







Fig. 3, Vertical Tubular Boiler, with Fuel-Length Tubes. 



SA 



QUESTIONS AND ANSWERS 



Ans. — By stay-bolts connecting with the shell and th< 
back head. The small tubes serve as stays for the front 
sheet. 




Fig. 4. Vertical Marine Boiler, Showing Details 
of Bracing. 



Ques. 94. — What is meant by double-ended Scotd 
boilersf 

Ans. — Boilers having furnaces at each end. A double- 
ended Scotch boiler is in fact two single-ended boilen 
placed back to back. 



THE BOILER 



31 



Ques. 95. — What advantage has the Scotch boiler 
over other types? 

Ans. — A very large amount of heating surface in 
proportion to its cubic contents. 

Ques. 96. — What are the disadvantages connected 
with the use of the Scotch boiler? 




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Fig. 5. Single-Ended Scotch Marine Boiler. 



Ans. — First, defective water circulation; second, 
iability to leaky tubes; third, unequal expansion of the 
)arts, thereby setting up severe strains. 

Ques. 97. — Is the Scotch boiler much used? 

&ns. — It is in almost universal use in the large ocean- 
orng mercnanr vessers. 



32 



QUESTIONS AND ANSWERS 



Ques. 98. — What are the distinctive features of the 
flue and return-tube boiler? 

Ans. — This form of boiler is cylindrical in shape in 
that part of the shell containing the large flues and 
small return tubes, but resembles a locomotive boiler in 
that portion containing the fire-box. 





Fig. 6. Double-Ended Scotch Marine Boiler, Sectional View. 

Ques. 99. — Describe the action of the heat in this 
boiler. 

Ans. — The furnace or fire-box, resembling that of a 
locomotive, is located in the front end of the boiler. 
From thence large flues conduct the heated gases to the 
combustion chamber in the rear, similar to that of a 
Scotch boiler, and from there the gases return through 
the small tubes to the uptake. 



THE BOILER 



3* 




S 

« 
o 

u 

w 

(4 
P 

w 
CCS 



6 



34 



QUESTIONS AND ANSWERS 



Ques. 100. — Describe the Western river boiler. 

Ans. — This boiler is usually very long (25 to 30 feet) 
ji proportion to its diameter. It consists of a cylindrical 
shell having two or more flues of large diameter (12 to 
14 inches) extending its entire length. It is set in brick- 
work in the same manner as the horizontal tubular boiler 
is, tie gases passing underneath the shell to the rear, and 
thence returning through the large flues to the uptake 




Fig. 8. The Bonus-Freeman Water-Tube Boiler. 

leacirg to the stack. It is a very simple boiler, and willj 
withstand high pressures and hard usage. 

Ques. 101. — Describe the locomotive boiler. 

Ans. — The locomotive boiler consists essentially of al 

rectangular fire-box and a cylindrical shell. A large 

number of tubes of small diameter (2 inches) -?ass| 

through the shell from the fire-box to the smoke-box, 

continuation of the barrel at the front end. 



THE BOILER 



3» 




36 



QUESTIONS AND ANSWERS 



Ques. 102. — How is the fire-box joined to the outer 
shell at the bottom? 

Ans. — By a forged ring called the mud-ring, made of 
wrought iron or steel, through which long rivets pass, 
uniting the fire-box sheet and the outer sheet. 

Ques. 103. — How are the flat sides of the fire-box 
stayed? 

Ans. — By stay-blots screwed through the outer shell, 
into and through the fire sheet, and having both ends 
riveted down cold. 

Ques. 104. — How is the flat crown-sheet of a locomo- 
tive boiler stayed? 




P^5S^S-5s 



waaa 



L_ 



Fig. 10. Cornish Boiler. 



Ans. — By a system of crown-bars, made in the shape 
of double girders, the ends of which rest upon the side 
sheets of the fire-box. Crown-bolts pass up through the 
crown-sheet and crown-bars, and are secured by nuts 
resting upon saddles on top of the crown-bars. The 
heads of the bolts support the crown-sheet. 

Ques. 105. — Is the locomotive boiler an economical 
boiler for stationary purposes? 

Ans. — It is not. 

Ques. 106. — Are there any other forms of cylindrical 
•hell boilers besides those already referred to? 

Ans. — Yes; the Cornish boiler, having a large central 



THE BOILER 



31 



flue, in one end of which the furnace is located; the Lan- 
cashire boiler, a modification of the Cornish, containing two 
internal furnace flues, and the Continental boiler. 

Ques. 107. — What is meant by Galloway tubes as 
applied to a boiler? 

Ans. — Galloway tubes are conical-shaped water tubes 
which stand in an inclined position in the large flues of 
the Lancashire boiler back of the furnaces, and serve to 
circulate the water from the space below, to the space 
above the flues. They also act as bafflers to the gases In 
their passage through the flues, and thus provide increased 
heating surface. 








§§I?=is==sssrag 








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Fig. 11 The Lancashire Boiler. 



Pig. 12. The Gai^oway 
Boiler. 



Ques. 108. — Describe the Continental boiler. 

Ans. — The Continental boiler is a modification of the 
Scotch boiler, and is used to a large extent in the marine 
service. It is provided with a Morison corrugated fur- 
nace, and its efficiency as a steam generator has been 
established by a long series of practical tests. 

Ques. 109. — What are the leading characteristics of 
the Bonson boiler? 

Ans. — The Bonson boiler is a combination of the 
tubular and water-tube types. The water-tube member 
is in the form of a flat arch, and serves as a roof to the 
furnace. The cylindrical shell rests upon and is con- 



38 



QUESTIONS AND ANSWERS 



nected with front and rear steel saddles (water-chambers) 
and the water-tubes are connected with the lower portion 
of these saddles. * 

Ques 110. — What route do the gases take in passing 
from the furnace of the Bonson boiler to the smoke- 
stack? 




Fig. 13. Continental Boiler, with Morison Corrugated 
Furnace, eor Marine or Stationary Service. 



Ans. — They pass first under the water-tubes, which 
are lined with a special tile made of fire-clay, the sides of 
the furnace being also lined with fire-brick. The gases, 
after passing into the combustion chamber, at the rear, 
ascend and return through the fire-tubes in the shell, and 
from thence into the uptake at the front. 

Ques. 111. — What are the leading characteristics of 
water-tube boilers? 



v 



THE BOILER 



39 



Ans. — In water-tube boilers the larger part of the 
heating surface consists of tubes of moderate size (1 to 4 
inches in diameter). There is always some form of 
separator, drum or reservoir into which the tubes lead. 
In this drum the steam is separated from the water. In 
some forms of water-tube boilers this shell or drum is of 
considerable size. 




Fig. 14. The Bonson Boiler and Setting. 

Ques. 112. — Is this drum exposed directly or indi- 
rectly to the heat? 

Ans. — It is generally exposed indirectly, as the upper 
part is used for steam space. 

Ques. 113. — What advantage is there in having a 
large size steam and water-drum? 

Ans. — The advantage of having a good free water 
surface for the disengagement of the steam. The water 
occupies about one-third of the lower portion of the drum. 



iO QUESTIONS AND ANSWERS 

Quef. 114. — Are the upper ends of the tubes in all 
water-trbe boilers entirely filled with water? 

Ans. — Not in all cases. In some forms of water-tube 
boilers the upper ends of the tubes extend above the 
water level. 

Ques. 115. — How are these different forms of water- 
tube boilers designated? 

Ans. — First, as drowned tubes; second, as priming 
\ubes. 




Fig. 15. Steee Saddle of Bonson Boieer. 

Ques. 116. — What are some of the advantages of 
water-tube boilers? 

Ans. — They may be made light, powerful and able to 
withstand high pressures. They are quick steamers, 
that is, steam may be raised rapidly from cold water; 
also, the circulation of the water in them is good gen- 
erally. 

Ques. 117. — What are some of the disadvantages 
attending the use of water-tube boilers? 

Ans. — They are difficult to inspect and clean. Also, 
owing to the large number of joints, leaks are liable to 
occur. 



THE BOILER 



41 



Ques 118. — Describe briefly the Babcock & Wilcox 
vater-tube boiler. 

Ans. — There is a large horizontal cylindrical shell at 
he top for the purpose of supplying steam and water- 
pace. The lower half of this shell contains water, and 
he upper half steam. The tubes are expanded into 
leaders at each end. At the front end these headers are 




Fig. 16. Babcock and Wilcox Boiler, for Land Service. 

rought up near the shell, to which they are connected 
y a cross connection. The back end headers are con- 
ected to a mud-drum at the bottom, and to the shell at 
he top by slightly inclined tubes. The back headers 
eing lower than the front headers, the tubes are thus 
nclined from front to back. 

Ques. 119. — In what style are the tubes connected to 
le headers? 

Ans. — They are staggered. 



42 



QUESTIONS AND ANSWERS 



Ques. 120. — What is meant by staggered tubes? 
Ans. — Staggered tubes are those which are not placed 
in vertical rows, that is, one directly above the other. 




Fig. 17. Babcock and Wilcox "Alert" Type Marine. Boiler. 
FromB. & W. "Book Marine Steam," p. 154. 

Ques. 121. — What are the facilities for cleaning thes< 
tubes? 

Ans. — At each end of each tube there are hand-hole: 
provided. 

Ques. 122. — Describe the course of the gases for th( 
Babcock & Wilcox boiler. 



THE BOILER 43 

Ans. — A brick bridge wall at the baca. tnu ot the fur- 
nace, together with special tiles placed among the tubes, 
compel the gases to first pass up among the tubes until 
they come in contact with the bottom of the shell for 
about two-thirds of its length from the front end. At 
this point a hanging bridge wall and special tiles deflect 
the gases downward in their course, and they again 
circulate among the tubes, passing underneath the tiles 
and up among the tubes again. The products of com- 
bustion thus pass over and around the tubes three times 
on their way to the uptake. 

Ques. 123. — What portions of this boiler constitute 
the heating surface? 

Ans. — The tubes, headers, and the lower half of the 
shell. 

Ques. 124. — What course does the water take in its 
circulation in this boiler? 

Ans. — Down from the shell at the rear to the water- 
tubes, thence forward and upward through the tubes. 
In its course through the tubes it becomes partially vap- 
orized and of less density. It then passes up into the 
shell at the front, where the steam is disengaged. 

Ques. 125. — Is the Babcock & Wilcox boiler much 
used in the marine service? 

Ans. — Yes, it is used extensively in the British and 
United States navies, also in merchant steamers. 

Ques. 126. — Is the form of this boiler the same for 
marine as for land service? 

Ans. — It is not. The chief features in which it differs 
from the land boiler are, first, a verv much larger grate 



44 



QUESTIONS AND ANSWERS 



area; second, the cylindrical shell is set transversely to 
the direction of the tubes; third, the fire-doors are located 
at what would be the rear of the land boiler; fourth, the 
tubes are much shorter, owing to the contracted space 
allowed on ocean steamers; fifth, the brickwork is sur- 
rounded outside by a metal casing. 




Fig. 18. The Caldweu, Boiler. 

Ques. 127. — Are there any other forms of water-tube 
boilers patterned after the Babcock & Wilcox boiler? 

Ans. — There are several, prominent among which are 
the Caldwell and the Root boilers. 

Ques. 128. — Describe the Caldwell boiler. 

Ans. — It is similar in construction to the Babcock & 
Wilcox, except that the tubes, instead of being staggered 
vertically, are placed one directly above the other, with 
specially shaped fire-brick laid across alternate spaces 
between the tubes to deflect the gases. 



THE BOILER 



45 



Ques. 129. Describe the Root water-tube boiler. 

Ans. — It consists of a nest of 4-inch tubes expanded 
into headers which are connected at front and back with a 
set of steam and water-drums about 15 inches in diameter. 
The tubes are inclined at an angle of about 20 degrees 
from the horizontal. At the rear end of each overhead 
water and steam-drum is a connection leading to the 




■■■ 



Fig. 19. The Root Water-Tube Boiler. 

steam-collecting header above, placed transversely to the 
direction of the other drums, and from this header two 
connecting pipes lead to a large steam-drum located at 
about the center of the boiler, and above all. 

Ques. 130. — How does the water circulate in the Root 
boiler r 

Ails. — It descends through vertical connecting pipes 
If rom the feed-drum at the rear to the mud-drum beneath^ 



46 



QUESTIONS AND ANSWERS 



From thence it passes into the back and lower ends of the 
tubes, and on up through the tubes, and into the over- 
head drums, into the upper halves of which the steam is 

disengaged. 

Ques. 131. — Describe the Cahall water-tube boiler. 
Anc —The Cahall boiler is vertical, having a nest of 




Fig. 20. The Cahall Vertical Boiler. 



water-tubes standing nearly vertical. These tubes are 
connected with a shallow water-drum at the bottom, and 
a larger and deeper water and steam-drum at the top. 
The furnace is located alongside of the mud-drum, and 
the gases traverse among the tubes in a circuitous manner 
owing to bafflers placed among the tubes. 



THE BOILER 4T 

Oues. 132. — How do Lie £*ses escape to the stack . ; a 
his boiler? 




Fig. 21. -Wickes Vertical Water-Tube Boiler. 



Ans. — Extending through the center of the annular 
rum at the top is a flue through which the products of 
ombustion find their way to the uptake. 



48 



QUESTIONS AND ANSWERS 



Ques. 133. — Of what form is the Wickes boiler? 

Ans. — The Wickes boiler consists of upper and lower 
vertical drums connected by vertical tubes. The furnace 
is external. 




Fig. 22. The Stirling Boiler. 

Ques. 134. — What course do the gases take in their 
passage to the stack, in the Wickes boiler? 

Ans. — A thin partition wall of fire-brick is built 
between two adjoining middle rows of tubes. This wall 
causes the erases first to ascend to the top, and then down- 



THE BOILER 



4& 



wards to the chimney flue at the bottom and opposite to 
the furnace. 

Ques. 135. — Describe the Stirling boiler. 

Ans. — In the Stirling water-tube boiler there are 
three horizontal steam and water-drums at the top, an^ 




Fig. 23. Thornycroft Boiler. 



one water-drum at the bottom. These drums are co** 
nected by three divisions of inclined and curved tubes. 

Ques. 136. — How are the products of combustion led 
from the furnace to the uptake, in the Stirling boiler? 

Ans. — Bafflers of fire-brick are placed back of the two 
first divisions of tubes. The first baffler cause* the gases 



50 



QUESTIONS AND ANSWERS 



to ascend to the top of the first division of tubes; the 
second baffler deflects the gases downwards, around and 
among: the tubes of the second division. The draught is 
tlw : i upwards again, surrounding the tubes composing 
tb' third division, thence to the stack. 




Fig. 24. The Niclausse Boiler. 

Ques. 137. — Describe the Thornycroft boiler. 

Ans. — The Thornycroft boiler is adapted for use on 
torpedo boats and high-speed yachts. A large horizontal 
steam-drum at the top is connected to a water-drum at 
the bottom by two groups of curved tubes of small 



THE BOILER 



51 



diameter. The grates are located on each side of the 
water-drum. There are also two smaller drums at the 
bottom, one on each side, connected to the middle drum 
by small pipes. 




Fig. 25. The Niceausse Boiler— Side View. 

Ques. 138. — How does the water circulate in this 
boiler? 

Ans. — Down from the top drum to the middle lower 
drum through special return water-tubes of large 
diameter, and from thence through the smaller tubes to 



52 QUESTIONS AND ANSWERS 

the side drums. From there the water passes up through 
the curved tubes to the upper portion of the top drum, 
where the steam is disengaged. 

Ques. 139. — Describe the Niclausse boiler. 

Ans. — The Niclausse boiler is made up of a series of 
slightly inclined tubes. These tubes are double, that is, 
one inside the other, and they are connected to the front 
header in such a manner that the colder water flows down 
the inside tubes and returns to the front between the two 
tubes when heated by the action of the fire and hot gases 
on the larger outside tubes. Each vertical row of tubes 
is connected at the front end to a separate header, the 
headers being placed side by side, and all leading into a 
top drum or steam-collector. 

Ques. 140. — How is the entering feed-water at the 
front kept separate from the hot ascending currents of 
water? 

Ans. — By a diaphragm in the top drum that keeps the 
cooler water separate from the hot water and steam. 

Ques. 141. — How are the tubes connected to the 
headers in the Niclausse boiler? 

Ans. — By coned surfaces on the ends of the tubes 
bearing on similar coned surfaces in the headers, and kept 
in contact by outside dogs and nuts. These joints 
appear to cause no trouble by leakage. 

Ques. 142. — Is the Niclausse boiler much used? 

Ans. — It is used to some extent in the British navy, 
and also in several large United States war-ships. 

Ques. 143. — Of what type is the Normand boiler? 

Ans. — The Normand boiler is a marine water-tube 



THE BOILER 



53 



boiler of the Thornycrof t type. The two outer rows of 
tubes are formed into a wall of tubes, and in the vicinity 
of the furnace the tubes are arched upwards in order to 
form a combustion chamber. Back of the furnace the 



Part front "View 



Part section through 
furnace. 




Fig. 26. The Normand Boiler. 



curvature is not so great, although all of the tubes are 
curved more or less, to permit of expansion when heated. 
Ques. 144. — What course do the gases take in this 
boiler? 



b'4 



QUESTIONS AND ANSWERS 



Ans. — The gases proceed from the fire among the 
tubes, and traverse the length of the boiler to the rear 
end, where they pass below a brick deflecting plate to 
the space surrounding those tubes that are less curved. 




Fig. 27. The Yarrow BoitER. 

Ques. 145. — What other peculiar feature character- 
izes the Normand boiler? 

Ans. — Provision is made for tne admission of air 
Aoove the fire. 



THE BOILER 55 

Ques. 146. — How is this accomplished? 

Ans. — By means of a small air casing at the front and 
back, and a series of small holes one inch in diameter lead- 
ing through the brickwork to the space above the fire. 

Ques. 147. — For what kind of service is the Normand 
boiler mainly adapted? 

Ans. — For torpedo-boat destroyers. 

Ques. 148. — What is the distinguishing feature of the 
Yarrow boiler, among boilers having water-tubes of small 
diameter? 

Ans. — The Yarrow boiler lias straight tubes. It also 
has at the bottom on each side a small water-chamber or 
mud-drum with nearly flat tube-plates, into which the 
tubes are expanded. The tubes run in an inclined direc- 
tion from these water-drums to the steam and water- 
drum at the top. 

Ques. 149. In what manner does the water circulate 
in the Yarrow boiler? 

Ans. — Those tubes which receive the most heat con- 
duct the water from the lower drums to the upper drum, 
into which the steam is delivered. Other tubes which 
are cooler carry the water from the upper drum to the 
lower drums. 

Ques. 150. — Describe the Mosher boiler. 

Ans. — The Mosher boiler has two upper steam-drums 
and two lower and smaller water-drums, the water- 
drums being directly underneath the steam-drums. These 
drums are connected by curved generator pipes of small 
diameter, the pipes entering the steam-drums above the 
water-line. 



56 



QUESTIONS AND ANSWERS 



Ques. 151. — How does the water find its way from 
the upper to the lower drums? 

Ans. — By means of two external downtake pipes 
4 inches in diameter. The boiler is cased in, the casing 
being lined with fire-brick. 

Ques. 152. — For what class of service is the Mosher 
boiler mainly adapted? 

Ans. — Torpedo boats and high-speed yachts. 




Fig. 28. The Mosher Boiler. 



Ques. 153. — Describe the construction of the Almy 
boiler. 

Ans. — It is made principally of short lengths of pipe 
screwed into return bends and into twin unions. At the 
bottom there is a larger pipe or header that surrounds 
the two sides and back of the grates, and there is a 
similar structure at the top, the two headers being con- 
nected by the smaller pipes. 



THE BOILER 



5? 



Ques. 154. — How is the steam separated from the 
water in the Almy boiler? 




Fig. 29. The Aemy Boiler. 



Ans. — The steam and water are together discharged 
from the upper header into a separator in front of the 
boiler, and from this separator the steam is drawn, while 



58 



QUESTIONS AND ANSWERS 



the separated water and the feed-water pass down 
through circulating pipes to the lower header. 

Ques. 155. — What other peculiar feature attaches to 
this boiler? 




Fig. 30. The Du Temple Boiler. 

Ans. — It is provided with a coil feed-water heater 
above the main boiler. 

Ques. 156. — Describe in general terms the Du Tempi 
boiler. 



THE BOILER 



59 



Ans.— It is of the same general character as the 
'hornycroft type, except that the generating tubes dis- 
harge into the steam-drum below the water-line. 

Ques. 157. — How are these tubes connected to the 
trums? 




Fig. 31. Rsed's Boiler. 



Ans. — By cones and nuts. 

Ques. 158.— Is the Du Temple boiler used to any 
;reat extent? 

Ans. — Yes; it is used extensively in the French navy, 
specially on vessels of the torpedo-boat type. 

Ques. 159.— Describe Reed's boiler. 



60 



QUESTIONS AND ANSWERS 



Ans. — This boiler resembles the Du Temple boiler. I 
has the usual top collector drum, and two lower drum 
with curved generating pipes connecting them. 

Ques. 160. — How are the tubes attached to th 

drums? 




Fig. 32. The Seabury Boiler. 

Ans. — By screwed connections at each end, witl 
nuts inside the chambers. 

Ques. lGl.-^-How are the gases caused to travers< 
the heating surface in this boiler? 

Ans. — By means of diaphragms fitted to the tubes. 

Ques. 162. — What class of service is this boile: 
largely used in? 



THE BOILER 61 

Ans. — British torpedo-boat destroyers, and also on 
hird-class cruisers. 

Ques. 163. — Describe the Seabury boiler. 

Ans. — The Seabury boiler has three lower water- 
rums, the middle drum being smaller than the two out- 
ide drums. These drums are connected to one large 
team and water-drum above by curved pipes of small 
iameter and the furnace is divided into two sections by 
he central nest of pipes. Above the boiler tubes and 
nside the casing there is a coil feed-water heater. 

Ques. 164. — Describe the latest type of Belleville 
oiler? 

Ans. — The Belleville boiler is a water-tube boiler, and 
; of extensive use on large ships. It is made up of two 
istinct series of straight tubes, larger in diameter than 
hose of the curved type. These tubes are placed nearly 
orizontal, each alternate horizontal row being slightly 
nclined in the opposite direction to the row above it. 
The generator proper has a water-chamber below and a 
team-drum or chamber on top, and the zigzagged tubes 
re connected to these respective chambers, 

Ques. 165. — What kind of a furnace has this boiler? 

Ans. — A rectangular brickwork furnace inclosed in a 
teel casing, and the generating tubes are placed directly 
>ver the grates, the bottom row of tubes being about two 
eet above the grates. Baffle plates are secured at inter- 
als among the tubes for the purpose of causing the hot 
;ases to traverse the whole of the heating surface. 

Ques. 166. — How is circulation of the water secured 
n the Belleville boiler? 



6? 



QUESTIONS AND ANSWERS 



Ans. — By means of external return water-pipes, one 
on each side connecting the ends of the top drum with 
♦be lower water-chamber, the cooler water thus passing 

Teed/ outlet 



Feed inlet to Boiler 
cfter leaving 
iconom/ser* 




Fig. 33. BellevwAB Bviui* wii* Economise*. 



THE BOILER 63 

down through these pipes into the lower drum, and from 
thence the heated water passes up through the generating 
tubes, discharging into the top drum, where the steam is 
disengaged. 

Ques. 167. — What are the usual dimensions of the* 
generating tubes? 

Ans. — Four and one-half inches in diameter and seven 
feet six inches in length. The ends are connected by- 
being screwed into malleable cast-iron boxes. 

Ques. 168. — How is the economizer or feed-water 
heater attached to this boiler? 

Ans. — It is placed directly above the generator, a 
space called the combustion chamber being left between 
the two series of tubes. The tubes of the economizer are 
smaller, being 2}i inches in diameter. The general form 
of the economizer resembles that of the generator. 

Ques. 169. — What is the course of the feed-water in 
this boiler? 

Ans. — It enters the bottom of the economizer and is 
forced upwards to and fro through the zigzagged tubes 
to the top, and from thence it falls to the bottom of the 
hot water collector at the top, and then flows to the 
return pipes, through which it passes to the generator. 

Ques. 170. — -Mention another peculiar feature of this 
boiler. 

Ans. — An automatic feed-regulating device worked 
by a float in a chamber acting upon the feed-valve. 

Ques. 171. — Is the Belleville boiler an economical 
boiler? 

Ans. — It is; an actual evaporation of from 9.3 poun^j 



64 



QUESTIONS AND ANSWERS 



to 9.9 pounds of water per pound of coal having been 
obtained under test, with the feed-water at a temperature 
of 68 degrees. 

Pipe connected to 
upper part of element 




view of A 



JFeeol inlefr. 



U. Aotomatic Feed Regulator for Belleville Boiler. 



^ 



CHAPTER III 

BOILER CONSTRUCTION 

Ques. 172. — What is the best material to use in the 
construction of the shell of the boiler? 

Ans. — Open-hearth steel, having a tensile strength of 
from 55,000 pounds to 60,000 pounds per square inch. 

Ques. 173. — What is meant by the expression tensile 
strength (T- S.)? 

Ans. — The expression 60,000 pounds tensile strength 
means that it would require a pull of 60,000 pounds in 



I -CJ /£ 



Aboi/tz* 



I &-i£i!±-ya*&± i 

Fig. 35. Test Piece. 

the direction of its length to break a bar of the material 1 
inch square, or 2 inches wide by ^2 inch thick, or 2.67 
inches wide by Yz inch thick. 

Ques. 174. — How are steel sheets for boiler construc- 
tion tested? 

Ans. — A small piece, called a test piece, is cut from 
each sheet and placed in a testing machine. 

Ques. 175. — What is the working test for steel boiler 
sheets? 

Ans. — A piece from each sheet is heated to a dark 

65 



66 



QUESTIONS AND ANSWERS 



cherry red, plunged into water at 60° temperature, and 
bent double cold under the hammer, such piece to show 
no flaw or crack after doubling. 

Ques. 176. — Of what material should the tubes of 
fire-tube boilers be made? 

Ans. — A good quality of homogeneous iron. 

Ques. 177. — What is the working test for boiler tubes? 

Ans. — They should show no flaw when expanded into 
the flue-sheet and beaded. 




i^ I 




Fig. 36. Crow Foot Braces. 



Ques. 178. — What should the specifications be regard- 
ing rivets? 

Ans. — All rivet material should be of good charcoal 
iron, or mild steel, tough and soft. Test, a good rivet 
should bend double cold, without showing fracture. 

Ques. 179. — Of what material are the tubes of water- 
tube boilers usually made? 

Ans. — Of good charcoal iron or mild steel specially 
prepared for the purpose, and lap welded, or drawn. 



BOILER CONSTRUCTION 



67 



Ques. 180. — What is the test for tubes from 3 T A to 4 
inches in diameter and No. 10 wire gauge? 

Ans. — A piece V/2 inches in length is cut from one end 
of a tube, and this piece must stand hammering down cola 
vertically without showing a crack or split, when down 
solid. 

Ques. 181. — Of what material should stay-bolts be 
made? 

Ans. — Of iron or mild steel, especially manufactured 
for the purpose. 




Fig. 37. Gusset Stays. 

Ques. 182. — What should be the tensile strength of 
stay-bolt material? 

Ans. — For iron, not less than 46,000 pounds; for steel, 
not less than 55,000 pounds. 

Ques. 183. — What kind of material are braces and 
stays made of? 

Ans. — The material for braces and stays should be of 
:he same quality as the best stay-bolt stock. 

Ques. 184. — What is the object sought in staying the 
lat surfaces of a boiler internally? 

Ans. — The object is to strengthen those surfaces 

Iufficiently to enable them to withstand the maximum 
aternal working pressure to which thev will be subjected. 



68 



QUESTIONS AND ANSWERS 



Ques. 185. — Does the cylindrical portion of a boiler 
need bracing? 

Ans. — It does not, for the reason that the internal 
pressure tends to keep it cylindrical. 

Ques. 186. — What is the maximum direct pull per 
square inch of section that may be allowed on braces and 
stay-rods? 




Fig. 38. Through Stay Rods. 



Ans. — For iron, 6,500 pounds; for steel, 8,000 
pounds; and this point should be kept in view when spac« 
ing the braces. 

Ques. 187. — What is meant by spacing braces? 

Ans. — The distance from center to center that the 
stays are from each other at the point of their connection 
to the stayed surface. 

Ques. 188. — Give an example. 

Ans. — The stays in a certain boiler are spaced 8 inches 
apart, center to center, therefore each stay supports 



BOILER CONSTRUCTION 



69 



1x8=64 square inches. Assuming the working pressure 
o be 100 pounds per square inch, the sectional area of 
ach stay should be 1 square inch. 




f/M/IU(UJtrCQ-£4A 



Fig. 39. Vertical Tubular Boiler, with Submerged Tubes. 

Ques 189. — Suppose the working pressure is 250 
ounds per square inch and the stays are spaced 6 inches 



70 



QUESTIONS AND ANSWERS 



center to center, what should be the sectional area of eacF 
stay? 




Ans. — The pressure to be sustained by each stay would 
be 6x6 = 9000 pounds. Assume the stays to be of 



BOILER CONSTRUCTION 



71 



steel and unwelded, and allowing a direct pull of 7,200 
pounds per square inch, the sectional area of each stay 
should be tSBS = 1-25 square inches; or, if the stays are 
1.5 inches smallest diameter, and a direct pull of 8.000 
pounds per square inch of section is allowed, they may be 
spaced 7 inches, center to center. 

Ques. 190. — Of what forms are boiler stays usually 
made? 

Ans. — For low-pressure boilers, crow-foot stays; for 
high-pressure boilers, through stay-rods and gusset-stays. 




Fig. 41. Common Stay -Bolt. 



Ques. 191. — Where are stay-bolts used? 

Ans. — In fire-box boilers, and all boilers of the loco- 
motive type, to tie the fire-box to the external shell. 

Ques. 192. — How are stay-bolts applied? 

Ans. — A continuous thread is cut on the stay-bolt rod, 
the same thread being also tapped in the holes in the 
external plate, and the inside sheet. The steel stay-bolt 
is then screwed through the plates and allowed to project 
far enough at each end to permit of its being riveted down 
cold. 



72 



QUESTIONS AND ANSWERS 



Ques. 193. — What is the principal cause of the break 
ing of stay-bolts? 

Ans. — The unequal expansion of the sheets into which 
they are screwed. 

Ques. 194. — Why are stay-bolts sometimes drilled 
partly through their length? 

Ans. — In order that, if the bolt breaks, the steam or 
water may blow out through the small hole and give 
warning of the break. 

Ques. 195. — Describe the Tate flexible stay-bolt. 





Fig. 42. Tate Flexible Stay Bolt. 

Ans. — The outer head is ball shaped, and is inclosed 
within a socket formed by a sleeve that screws into the 
outer sheet and a cap that screws onto the sleeve. The 
other end of the bolt is screwed into and through the fire- 
sheet a sufficient distance to allow of riveting. 

Ques. 196. — What is meant by the efficiency of a 
riveted joint? 

Ans. — It is the per cent, of strength of the solid plate 
that is retained in the joint. 

Ques. 197. — What is the efficiency of a properly 
proportioned double riveted butt-joint? 



BOILER CONSTRUCTION 



73 



Ans. — From 71 to 75 per cent. 

Ques. 198. — What is the efficiency of a properly pro- 
portioned triple riveted butt-joint with inside and outside 
welts or butt-straps? 

Ans. — From 85 to 88 per cent. 




Fig. 43. Tate Feexibee Stay-Boi/t, Unthreaded. 

Ques. 199. — Where is the weakest portion of the triple 
riveted butt-joint? 

Ans. — At the outer row of rivets. 

Table 4 
Table of Diameters of Rivets* 



Thickness of 
Plate 


Diameter of Rivet 


Thickness of Plate 


Diameter of Rivet 


V4 inch 
8 /ie " 
3 / 8 " 

7 /l6 " 

% " 


V2 inch 

9/ i{ 

716 

n /l6 " 
3/ 4 « 

13 /l6 " 


9 /i6 inch 
Vs " 

S U " 

v. " 
1 " 


7 /s inch 

15 /l6 " 

IVm " 
IVs " 
l 1 /* " 



♦Machine design— W. C. Unwin. 

Ques. 200. — What percentage of efficiency may be 
retained in a properly designed quadruple riveted butt- 
joint having both inside and outside butt-straps? 

Ans. — 94 per cent. 



n 



QUESTIONS AND ANSWERS 



Ques. 201. — Where is the weakest portion of such 
joint? 

Ans. — At the outer row of rivets. 




Fig. 44. Double Riveted Butt-Joint. 

Ques. 202. — How may boiler heads be constructed 
which will not require to be stayed? 

Ans. — By being dished, or "bumped up." 




Fig. 45. Triple Riveted Butt-Joint. 



Ques. 203.— What is the depth of dish, as adopted by 
6teel-plate manufacturers? 



BOILER CONSTRUCTION 



75 



Ans. — One eighth of the diameter of the head, when 
langed. 

Ques. 204. — What should be the thickness of the head 
is compared to the thickness of the shell? 




Fig. 46. Quadruple Riveted Butt-Join t, 



Lloyd's rules, condensed, are as follows: 
,loyd's Rules — Thickness of Plate and Diameter of Rivets 



1 Thickness of 


Diameter of 


Thickness of 


Diameter of 


1 Plate 


Rivets 


Plate 


Rivets 


1 y% inch 


Vi inch 


Y\ inch 


7/$ inch 


1 7 /l6 


5/8 " 


13 /l6 " 


Vs " 


1 V* " 


Va " 


n - 


1 " 


1 °/l6 " 


Va " 


15 A« " 


1 " 


1 5 /8 " 


Va " 


1 " 


1 " 


1 Hie " 


% " 







Ans. — The heads should be as thick, or slightly thicker, 
tan the shell plate. 



76 



QUESTIONS AND ANSWERS 



Ques. 205. — What method other than riveting may- 
be, and sometimes is employed in the formation of boiler 
seams? 

Ans. — Boiler seams may be welded if the material 
from which the plates are rolled is of the best, and great 
care and skill are exercised. 

Ques. 206. — Mention two of the advantages possessed 
by welded seams over riveted seams? 

Table 5 

Proportions of Triple-riveted Butt Joints with Inside and 

Outside Welt 



Thickness of 


Diameter of 


Pitch of 


Pitch of 


Efficiency 
Per Cent 


Plate 


Eivet 


Rivet 


Outer Rows 


Inches 


Inches 


Inches 


Inches 


s / 8 


13 /l6 


3.25 


6.5 


84 


T /ii 


13 /l6 


3.25 


6.5 


85 


Vi 


13 /l6 


3.25 


6.5 


83 


%6 


Vs 


3.50 


7.0 


84 


5 / 8 


1 


3.50 


7.0 


86 


3 U 


lYii 


3.50 


7.0 


85 


% 


IVs 


3.75 


7.5 


86 


1 


1V 4 


3.87 


7.7 


84 



Ans. — First, a good welded joint approaches more 
nearly to the full strength of the material than can 
possibly be attained by rivets, no matter how correctly 
designed the riveted joint may be; second, the welded 
joint, having a smooth surface inside the boiler, is much 
less liable to collect scale and sediment than is the riveted 
joint. 

Ques. 207. — Why should the longitudinal or side 
seams of a boiler be stronger than the girth or round- 
about seams? 



BOILER CONSTRUCTION 7? 

Ans. — Because the force tending to rupture the boiler 
along the line of the longitudinal seams is proportional 
to the diameter divided by two, while the stress tending 
to pull it apart endwise is only one-half that, or propor- 
tional to the diameter divided by^four. 

Ques. 208. — What is the formula for ascertaining 

the bursting pressure of a boiler? 

TSXTXE _ . 
Ans. — 5 — B, in which 

TS = Tensile strength 
T = Thickness of sheet 
E = Efficiency of joint 
R = Radius (one-half the 

diameter) 
B = Bursting pressure 
Ques. 209. — How is the safe working pressure of a 
boiler ascertained? 

Ans. — First calculate the bursting pressure, then 
divide this by the factor of safety, which usually is five, 
although in some instances a safety factor of eight is used. 
Ques. 210. — In addition to the regular bracing and 
staying, how are the heads of return tubular and Scotch 
narine boilers greatly reenforced? 

Ans. — By the tubes, which are expanded into the 
leads and beaded down on the ends. 

Ques. 211. — Are the tubes always expanded into the 
ube-sheets? 

Ans. — They are in fire-tube boilers. In some forms 
>f water-tube boilers the tubes are screwed into the 
^ders or chambers. 



78 



QUESTIONS AND ANSWERS 



Ques. 212 — What type of furnace is largely used in 
internally fired boilers? 

Ans. — The Morison corrugated furnace. 

Ques. 213. — Mention three advantages gained by the 
use of corrugated furnaces. 

Ans. — First, the corrugations (if properly made) add 
great rigidity and strength to resist the crushing strain to 
which the furnaces are subjected; second, there is more 
heating surface in a corrugated than in a smooth surface; 
third : the alternate expansion and contraction of the 




Fig. 47. Section of Tube Expanded into Sheet. 

corrugated surface tends to loosen any scale that ma; 
form on the surface inside the boiler. 

Ques. 214. — In regard to riveted seams, which is th< 
better method, to drill or to punch the rivet-holes? 

Ans. — The rivet-holes should be drilled. In goo 
boiler work this method is now always followed. 

Ques. 215. — What other important point should bj 
kept in view in joining the plates of a boiler? 

Ans. — To get the joint tight without caulking, or a| 
least with as small an amount of caulkiner as oossible. 



BOILER CONSTRUCTION 



79 



Ques. 216. — Mention some of the injurious effects of 
excessive caulking. 

Ans. — First, it is one of the most fruitful causes of 
grooving along the edges of the seams; second, it tends 
to raise the edge of the plate that is caulked, thereby 
causing looseness at the joint. 

Ques. 217. — What other very important point should 
be secured in the construction of the boiler? 

Ans. — The rivet-holes in the plates should come fair 
before the rivet is put in. 



^^ X. * -^ -^"/ V r '-:^v^ -: v**',i/"\-/ -#*' -' 



Fig. 48. Morison Corrugated Furnace. 

Ques. 218. — If the rivet-holes do not come fair what 
should be done with them? 

Ans. — They should be made exactly true by the use of 
a rimer. 

Ques. 219. — What should not be done with the rivet- 
holes in case they do not come fair? 

Ans. — They should not be drifted. A drift-pin is 
often the primary cause of starting a crack in a sheet. 

Ques. 220. — What can be said generally concerning 
the construction of a boiler, especially one intended for 
high pressures? 



80 QUESTIONS AND ANSWERS 

Ans. — Only the best material should be used, and 
great care and skill should be exercised in all the detail 
of assembling it. 

By reference to Chapter I, Part 2, of Swingle's 
"Twentieth Century Hand Book for Engineers and Elec- 
tricians," the student will be enabled to obtain much 
more detailed information concerning boiler construction, 
the strength of riveted joints, bracing and staying, 
strength of material, etc., as all of these important feat- 
ures are dwelt upon at length and fully discussed. 



CHAPTER IV 

BOILER SETTINGS AND APPURTENANCES. 

Ques. 221. — What kind of a setting is required for 
internally fired boilers? 

Ans. — First, a good solid foundation, second, the 
Doiler should be covered with non-conducting, non-com- 
Dustible material of some sort, to prevent radiation of 
heat, and the whole should be encased in a sheet-metal 
jacket. 




mm 



m 




Fig. 49. Plan and Elevation oe Boiler Setting, Showing Air Spaces. 

Ques. 222. — What kind of a setting is required for 
horizontal tubular and water-tube boilers? 

Ans. — Brick walls with an inner lining of fire brick. 
When the boiler is supported by lugs resting upon 
the walls, a heavy iron plate should be imbedded in the 
brickwork, for each lug to rest upon. The walls should 
also be tied together, both endwise and transversly, by 
iron rods not less than 1/4 inch in diameter, extending 
clear through in both directions, the bottom rods to be 
laid in place as the walls are being built. These rods are 
\o have a thread and nut on each end, and are secured 

81 



82 



QUESTIONS AND ANSWERS 



to heavy cast or wrought iron bars called buck stays, 
placed vertically against the outside of the walls. 

Ques. 223. — How may boiler walls be greatly pro- 
tected from the injurious action of the heat? 

Ans. — By leaving an air-space of 2 inches between the 
fire-brick lining and the outer wall, beginning at the 
level of the grate bars and extending as high as the cen- 
ter of the boiler. Above this height the walls should be 
solid. 



■4*\ 




Fig. 50. Clamp for Back Arch. 



Ques. 224. — What is the duty of bridge-walls and 
bafflers? 

Ans. — To present a hot surface for the unconsumed 
gases to impinge against, and also to divert the gases 
towards the heating surface of the boiler. 

Ques. 225. — How may a good and durable back arch 
for a horizontal tubular boiler be constructed? 

Ans. — Take flat bars of iron H inch thick by 4 inches 
ua width, cut them to the proper length, bend them to the 



BOILER SETTINGS AND APPURTENANCES 



8J 



shape of an arch, and turn 4 inches of each end back at 
right angles. The clamp thus formed is to be filled with 
a course of side arch fire-brick, and will form a complete 
and self-sustaining arch 9 inches wide and with sufficient 
spring to cover the distance between the back wall and 
the back head of the boiler above the tubes. Enough of 
these arches should be made so that when laid side by 
side they will cover the distance from one side wall to 
the other, across the rear end of the boiler. 




Fig. 51. Back Arch Complete. 

Ques. 226. — What advantages do this form of back 
arch possess over the ordinary flat cover? 

Ans. — First, it can come and go with the expansion 
and contraction of the boiler; second, it always maintains 
a practically air-tight cover at this important point; 
third, in case of needed repairs to the back end of the 
boiler the sections may be easily removed, one at a time, 
and when the repairs are completed they may be reset with 
very small expense. 



84 



OURSTIOXS AND ANSWERS 



Ques. 227. — Give an easy rule for ascertaining the 
dimensions of the grates. 

Ans. — For a horizontal tubular, the length of the 
grates should equal the diameter of the boiler. The 
width depends upon the construction of the furnace. If 
the fire-brick lining is built perpendicular, the width of 
grate will also equal the diameter of the boiler, but if 




Fig. 52. Back Arch in Pi«ace. 

the lining is given a batter of 3 inches, starting at the 
level of the grates, then the width of grate will be 6 
inches less. 

Ques. 228. — What is the ordinary ratio of grate sur- 
face to heating surface for land boilers, with natural 
draught? 

Ans. — One square foot of grate surface to every 36 
square feet of heating: surface. 



BOILER SETTINGS AND APPURTENANCES 



85 



Ques. 229. — What ratio of grate surface to heating 
surface is usually chosen with forced draught? 

Ans. — One square foot of grate surface to 40 square 
feet of heating surface, and in some instances the ratio 
is as high as 1 to 50. 

Ques. 230. — How many different styles of grate-bars 
are in general use? 

Ans. — Four; first, the common stationary grate, 
consisting of a plain cast-iron bar tapered in cross 




PLAIN GRATE 

(STANDARD PATTIRN ) 




TUPPER OR HERRING-BONE CRATE 




SAW-DUST AND WOOD GRATF 

Fig. 53. Grate Bars. 



section and having small projections cast on the sides to 
keep the bars apart a sufficient distance; second, herring- 
bone grates, consisting of channel-shaped cast-iron bars 
having V-shaped openings on top to allow the air to pass 
through to the fire; third, shaking or rocking grates, 
fourth, dumping grates. 

Ques. 231. — What percentage of the total grate area 
is usually allowed for the admission of air through the 
grates? 



86 



QUESTIONS AND ANSWERS 



Ans. — From 30 to 50 per cent, depending upon the 
kind of coal used. 

Ques. 232. — What is the heating surface of a boiler? 

Ans. — All the surfaces that are in contact with and 
covered by water on one side and surrounded by flame or 
hot gases on the other side. The areas of these surfaces 
are estimated in square feet and added together. 




Fig. 54. M'Clave's Grates. 



PLATE NO 3. 




Fig. 55. M'Clave's Grates. 



Ques. 233. — Is it possible to estimate the horse-power 
of a boiler from its heating surface? 

Ans. — It is in a general way, but not accurately. 

Ques. 234. — How many square feet of heating surface 
are usually allowed per horse-power? 

Ans. — From 10 to 16 square feet, depending entirely 
upon the type of boiler. 

Ques. 235. — Give seme examples. 



BOILER SETTINGS AND APPURTENANCES 8? 

Ans. — For water-tube boilers 10 to 12 square feet of 
leating surface; for horizontal fire-tube, 12, for vertical 
iire-tube, 12 to 15, and for locomotive boilers, 12 to 16 
square feet of heating surface per horse-power. 

Ques. 236.— Why this difference? 

Ans. — Because the heating surface is more effective 
n some types of boilers than it is in others. 

Ques. 237. — What is the rule for calculating the heat- 
ng surface of a horizontal tubular boiler? 

Ans. — Taking the dimensions in inches, multiply two- 
:hirds of the circumference of the shell by its length. 
Multiply the inside circumference of one of the tubes by 
ts length, and this product by the number of tubes. Add 
hese two products together, and to this sum add two- 
hirds of the combined areas of both tube-sheets and 
rom this latter sum subtract twice the combined sec- 
ional areas of all the tubes. The result will be the 
leating surface in square inches, which, divided by 
.44, will give the number of square feet of heating 
urface. 

Ques. 238. — What is the rule for finding the heating 
urface of vertical fire-box boilers? 

Ans. — Multiply the circumference of the fire-box by 
ts height above the grate. Find the heating surface of 
he tubes by the process given in the former rule and add 
hese two products together, and to this add the area of 
he lower tube sheet. From this sum deduct the sectional 
rea of all the tubes. The dimensions having been taken 

inches, the result should be divided by 144 to ascertain 
e number of square feet of heating surface. 



88 QUESTIONS AND ANSWERS 

Ques. 239. — Why is the inside circumference of the 

tubes taken? 

Ans. — Because in fire-tube boilers this is the portion 
that is directly exposed to the heat. 

Ques. 240. — Why are the combined sectional areas of 
the tubes subtracted from the area of that portion of the 
tube-sheets that is exposed to the heat. 

Ans. — Because the effective heating surface of a 
tube-sheet is the surface remaining after the areas of the 
openings through the tubes is deducted. 

Ques. 241. — What is implied in the expression "a 
3-inch boiler tube?" 

Ans. — It means a tube 3 inches in external diameter. 

Ques. 242. — Such being the case, which diameter 
should be considered in calculating the heating surface of 
fire-tubes? 

Ans. — Only the inside diameter, which equals the out- 
side diameter minus twice the thickness of the tube. 

Ques. 243. — In calculating the heating surface of the 
tubes of water-tube boilers which diameter should be 
taken? 

Ans. — The outside diameter, for the reason that the 
outside circumference is exposed to the heat. 

Ques. 244. — How is the heating surface of a water- 
tube boiler ascertained? 

Ans. — Much depends upon the style of boiler. A 
general rule and one that will apply in all cases, is to 
multiply the outside circumference of one of the tubes by 
its length, and this product by the number of tubes that 
are of a similar length and diameter. If there are vari- 



his sections of tubes of va^v:ng lengths, the heating 
urface of each section must be ascertained separately 
nd the whole added together. To this sum must be 
dded the combined areas of those portions of the headers 
hat are directly exposed to the heat, having first deducted 
he sectional area of the tubes. All of those portions of 
he steam and water-drums that are directly exposed to 
he heat should be estimated as heating surface also. 



BOILER SETTINGS AND APPURTENANCES 



89 




Fig. 56 Door op a Belleville Boiler. 

The door proper has an outer and inner plate, the former being a screen plate 
nth edges open for the admission of air The door is perforated with holes at 
he lower part, through which the air is drawn, and the inner plate, which is of 
ast iron, is closed at the bottom, and has holes for the discharge of air at t:he 
op. When the fires are alight, there is a continuous current of air flowing into 
he furnace through these plates. 



Ques. 245. — What is the rule for ascertaining the 
eating surface of a Scotch boiler? 

Ans. — The grates being set in the large main flues, 
nly one-half of each flue area is available as heating 
urface. The following rule applies: To one-half the 
ombined area of the main flue add the area of one head 
between the grate and water-line, minus the total cross- 
ection of the tubes, plus one-half the cross-section of 



» 



QUESTIONS AND ANSWERS 



fc.dritt rfues, plus the combined inside area of the tubes, 
F*ms the inside area of the combustion chamber. 

Ques. 245. — Give the rule for finding the heating 
surface of a corrugated flue. 

Ans. — Multiply the average inside diameter in feet by 
the iength of the flue in feet, and this product by the 




Fig. 57. . 

Shows another variety, the air being admitted tht**C*fc holes at the bottom o 
the wrought-steel door proper, a perforated inner cast-ir^/i plate being fitted t< 
shield the door. The wrought-steel furnace frame which carries the door ai 
has an inner shield plate of cast-iron perforated with holes. 



constant 4.93. The result is square feet of heating 
surface. 

Ques. 247. — What is the duty of a safety valve? 

Ans. — To automatically relieve the boiler of all 
pressure above a certain prescribed working pressure b; 
allowing the surplus steam to escape into the atmosphere.| 

Ques. 248. — If a boiler had no safety valve, o r if th< 



BOILER SETTINGS AND APPURTENANCES 



91 



safety valve should refuse to work, and all other exit 
from the boiler be closed, and heat continuously applied, 
what would be the result? 

Ans. — An explosion must of necessity occur. 




Fig. 58. Pop Vai^ve. 

Ques. 249. — How many types of safety valves are 
in use? 

Ans. — Two; the lever safety valve, and the spring- 
pop safety valve. 

Ques. 250. — Which is the best adapted to all kinds of 
service? 

Ans. — The spring-loaded pop safety valve is, for the 



92 



QUESTIONS AND ANSWERS 



reason that any inclination o* "~ L e boiler, such as that 
caused by the vessel's pitching ana rolling in a heavy sea, 
does not interfere with the working of a spring-pop valve, 




Fig. 59. Inside View of a Pop Safety Valve. 

while on the other hand the leverage of a weighted lever 
valve decreases with any inclination of the boiler that 



BOILER SETTINGS AND APPURTENANCES 



93 



would momentarily put the lever in an inclined position. 

Ques. 251. — What is the United States marine rule 
:or determining the area of lever safety valves for boilers? 

Ans- — "Lever safety valves to be attached to marine 
>oilers shall have an area of not less than 1 square inch to 




Fig. 60. Triplex Pop Safety Valve. 

very 2 square feet of grate surface in the boiler, and the 
seats of all such safety valves shall have an angle of 
inclination of 45 degrees to the center line of their axis." 
Ques. 252. — What is the rule regarding spring pop 
safety valves? 



94 QUESTIONS AND ANSWERS 

Ans. — f hree square feet of grate surface are allowed 
to each square inch of safety-valve area. 

Ques. 253. — What other and more reliable method is 
there of calculating safety-valve area? 

Ans. — The method by which the area of the valve is 
based upon the quantity of steam that the boiler is capable 
of generating. 

Ques. 254. — Why is this method more reliable? 

Ans. — For the reason that the rate of combustion 
varies greatly under different conditions, as, for instance, 
when forced draught is employed, a much higher rate of 
combustion is attained than is possible with natural 
draught. 

Ques. 255. — Do the standard rules given in answers 
251 and 252 hold good for safety-valve areas for all 
pressures? 

Ans. — No; because the rate of efflux for steam 
increases as the pressure increases. Therefore, for the 
higher pressures the total safety-valve area may be 
reduced. 

Ques. 256. — What should be the lift of a safety valve 
in order to allow the proper area of escape? 

Ans. — One-fourth of the diameter of valve. 

Ques. 257. — What is the rule for ascertaining the 
pressure at which a lever safety valve will lift when the 
weight and its distance from the fulcrum are known, as 
also the effective weight of the valve, stem, and lever? 

Ans. — Multiply the weight by its distance from the 
fulcrum. Multiply the weight of the valve and lever by 
the distance of the stem from the fulcrum, and add to the 






BOILER SETTINGS AND APPURTENANCES 



95 



>rmer product. Divide the sum of the two products by 
le product of the area of the valve multiplied by its dis- 
mce from the fulcrum. The result will be the pressure 
i pounds at which the valve will lift. 

Ques. 258. — What is the rule for finding the distance 
lat the weight should be placed from the fulcrum for a 
jquired pressure? 

Ans. — Multiply the area of the valve by the pressure 




Fig. 61. Davis Belt Driven Feed Pump. 



t which it is desired to have it lift, and from this product 
ibtract the effective weight of the valve and lever, 
lultiply the remainder by the distance of the stem from 
le fulcrum, and divide by the weight. The quotient will 

the required distance. 

Ques. 259. — What is the rule for ascertaining the 
eight required when all of the other factors are known? 



96 



QUESTIONS AND ANSWERS 



Ans. — Multiply the area of the valve by the pressure, 
and from the product deduct the effective weight of the 
valve and lever. Multiply the remainder by the distance 
of the stem from 'the fulcrum and divide by the distance 
of the ball or weight from the fulcrum. The quotient 
wiU be the required weight in pounds. 







Fig. 62. Phantom View oe Marsh Independent Steam Pump. 

Ques. 260. — What can be said in general regarding 
the safety valve? 

Ans. — It is one of the most useful and important 
adjuncts of a steam boiler, and if neglected, serioas 
results are apt to follow. 

Ques. 261. — Mention the two standard methods of 
supplying the feed-water to boilers under pressure? 

Ans. — First, by the feed-pump; second, by the 
injector. 



BOILER SETTINGS AND APPURTENANCES 97 

Ques. 262. — What advantage has the feed-pump over 
the injector? 

Ans. — The advantage of being able to draw its supply 
of water from a heater, in which the exhaust steam is 
utilized for heating the feed-water before it enters the 
boiler. Great economy in fuel is thereby effected. 

Ques. 263. — What is a duplex pump? 

Ans. — A duplex pump consists of two steam-cylinders 
and two water-cylinders, each having the necessary 
pistons and valves. The steam-valves of one side are 




Fig. 63. Worthington Duplex Boiler Feed Pump. 

operated by the other side, and vice versa. Both water 
cylinders discharge into the same main. A common 
suction main serves both water-cylinders also. 

Ques. 264. — If one side of a duplex pump becomes 
disabled from any cause, how may the other side be 
operated for the time being? 

Ans. — Loosen the nuts or tappets on the valve-stem of 
the broken side and place them far enough apart so that 
the steam- valve will be moved through only a small por- 
tion of its stroke, thereby admitting only steam enough to 
move the empty steam-piston and rod, and thus work the 



98 



QUESTIONS AND ANSWERS 



steam-valve of the remaining side. The packing on the 
piston-rod of the broken side should be screwed up 
tightly, so as to create as much friction as possible, there 
being no resistance in the water end. In this manner the 
pump may be operated for several days or weeks, and 
thus prevent a shut-down. 




OVERFLOW 



SUCTION 

Fig. 64. The Hancock Inspirator. 



Ques. 265. — How is the velocity of flow, or piston* 
;peed per minute of a pump ascertained? 

Ans. — Multiply the number of strokes per minute by 
the length of stroke in feet, or fractions thereof. This 
will give the piston-speed in feet per minute. 

Ques. 266. — How is the velocity of flow in the dis- 
charge-pipe ascertained? 

Ans. — Divide the square of the diameter of the water* 



k 



BOILER SETTINGS AND APPURTENANCES 



99 



:ylinder in inches by the square of the diameter of the 
iischarge-pipe in inches, and multiply the quotient thtia 



831109 OJL 




obtained by the piston-speed in feet per minute of the 



pump. 



Ques. 267.— When the velocity in feet oer minute If 



100 



QUESTIONS AND ANSWERS 



koown, how may the number of cubic feet discharged 
per minute be ascertained? 

Ans. — Multiply the area of the pipe in square inches 
by the velocity in feet per minute, and divide by the con- 
stant 144. The result will be the number of cubic feet of 
water or other fluid discharged per minute. 

Ques. 268. — How may the required size and capacity 
of feed-pump for a certain boiler be ascertained? 




Fig. 66. The Self- Acting Injector 



Ans. — Multiply the number of square feet of grate 
surface by the number of pounds of coal it is desired to 
burn per hour per square foot of grate. This will give 
the total coal consumed per hour, which, multiplied by the 
number of pounds water evaporated per pound of coal 
will result in the total number of pounds water required 
per hour. 

Ques. 269. — How may the required size of the feed- 
pump be ascertained from the number of square feet of 
heating surface? 



BOILER SETTINGS AND APPURTENANCES 



101 



Ans. — Allow a pump capacity of 1 cubic foot of watei 
per hour for each 15 square feet of heating surface. 

Ques. 270. — How can an injector lift and force watei 




into the boiler against the same or even higher pressure 
than the pressure of the steam supplied to the injector? 

Ans. — An injector works because the steam imparts 
sufficient velocity to the water to overcome the pressure 
in the boiler. 



102 



QUESTIONS AND ANSWERS 



Ques. 271. — What is the velocity of a jet of steam 
under 180 pounds pressure issuing from a nozzle? 

Ans. — About 3,600 feet per second. 

Ques. 272. — What is the velocity of a jet of water 
under a pressure of 180 pounds issuing from a nozzle? 




Ans. — Only 164 feet per second. 

Ques. 273. — Why docs the steam have so much 
greater velocity than the water, when the pressure in both 
instances is the same? 



BOILER SETTINGS AND APTORTENANCES 



103 



Ans. — Because of the latent heat that is stored in the 
steam. 

Ques. 274. — What is the purpose of the combining 
tube in an injector? 

Ans. — To bring the jet of steam and the jet of water 
into close contact in order that the steam may be con- 




WA.TEP 
CONN *TO* 



Fig. 69. Water Column. 

densed and the size of the jet reduced sufficiently to allow 
it to enter the delivery tube, which is of smaller diameter 
than the combining tube. 

Ques. 275. — What is the velocity of the combined jet 
of water and condensed steam as it leaves the combining 
tube and enters the delivery tube, assuming the steanr 



104 QUESTIONS AND ANSWERS 

pressure in the boiler to be 180 pounds per square 
inch? 

Ans. — 198 feet per second. 

Ques. 276. — What velocity is actually needed to cause 
the jet to enter the water-space of the boiler carrying 180 
pounds pressure? 

Ans. — Only 164 feet per second. The excess of 
34 feet per second imparted to the velocity of the jet 
serves to overcome the friction of the feed-pipe and 
the resistance of the main check-valve. 

Ques. 277. — In general terms, then, to what is the 
action of the injector due? 

Ans. — The action of the injector is due to the high 
velocity with which a jet of steam strikes the water enter- 
ing the combining tube, imparting to it its momentum 
and forming with it during condensation a continuous jet 
of smaller diameter, having sufficient velocity to over- 
come the pressure in the boiler. 

Ques. 278. — What is the object in fitting a boiler with 
a check-valve in the feed-pipe? 

Ans. — A check-valve is for the purpose of preventing 
the water in the boiler from backing up into the feed 
main and feed-pump. 

Ques. 279. — Where should the check-valve be located? 

Ans. — In the feed-pipe, as near to the boiler as 
possible. 

Ques. 280. — For what purpose are gauge-cocks and 
water-gauge glasses? 

Ans. — They are for the purpose of indicating the 
height of the water in the boiler while it is under pressure. 



BOILER SETTINGS AND APPURTENANCES 



105 



Ques. 281. — Describe the construction and operation 
of a glass water-gauge? 

Ans. — A water-gauge, otherwise known as a water 
column or combination, is a cast-iron or brass cylinder 
connected to the steam-space of the boiler at the top, and 
to the water-space near the bottom. The normal position 
of the safe water-level is near the middle of the water- 





Fig. 70. Ivow Water Alarm. 



Fig. 71. Combined High and 
how Water Aearm. 



column, into one side of which are screwed brass fittings 
for the glass tube or water-glass, which is a strong tube 
of special manufacture. Each end of this tube passes 
through a stuffing box in the brass fittings. The joint 
is made steam tight by a rubber ring that fits around 
the tube and is compressed by a follower screwed onto it. 
The fittings that connect the water-column with the boiler 
are, or at least should be, equipped with automatically 
closing ball valves which will act in case the gauge-glass 
breaks. 



10G QUESTIONS AND ANSWERS 

Ques. 282. — Where are the gauge-cocks or test-cocks 
usually connected? 

Ans. — They are usually connected to the water-column 
cylinder in such a position that the lowest one is at the 
desired water-level, one a few inches above that, and the 
third near the highest point of the heating service. These 
test-cocks should be opened several times a day in order 
to keep them clear for use in case the gauge-glass breaks. 

Ques. 283. — What is liable to happen to the water- 
column? 

Ans. — Unless the water and sediment are frequently 
blown out of it through the valve at the bottom provided 
for this purpose, the tubes and connections will become 
clogged, thus preventing a free circulation of the water, 
and the true water-level in the boiler will not be indicated 
as it should be. 

Ques. 284. — What is a fusible plug? 

Ans. — A fusible plug is a 1-inch brass pipe threaded 
plug, having its center drilled out to a diameter of not 
less than /^ inch, and the hole filled with Banca tin or 
other fusible metal. 

Ques. 285. — Where should a fusible plug be attached 
to a boiler? 

Ans. — A fusible plug should always be attached to 
that portion of the boiler that is first liable to become 
overheated on account of the water-level becoming too 
low. 

Ques. 286. — Mention some proper locations for fusible 
plugs in various types of boilers? 

Ans. — The back head of a horizontal tubular boiler. 



BOILER SETTINGS AND APPURTENANCES 



107 




about 3 inches above the top row of tubes, the crown- 
sheet of a horizontal fire-box boiler; the lower tube-sheet 
of a vertical boiler, or sometimes in one of the tubes a 
few inches above the tube-sheet; in the lower side of the 
upper drum of a water-tube boiler. The fusible metal 
which fills the center of the plug is of con- 
ical form in order to prevent its being blown 
out by the pressure behind it. On the other 
hand, the melting point of this fusible metal 
is such that when the water falls below it, 
and the steam under pressure in the boiler 
comes in contact with it, the metal is melted 
and runs out, thus allowing the steam to 
escape through the hole and give the alarm. 
If the melted plug is located in the crown- 
sheet of a fire-box boiler, the escaping 

steam and water will 
quench the fire and 
thus lessen the danger 
of burning the sheet. 





Fig. 72a. 

Klinger's Water Gauge Mounting.— The usual round thin gauge glasses 
give trouble with high-pressure steam, owing to frequent fractures, while the 
water level is often indistinct. Klinger's glass, designed to obviate these defects, 
gives promise of success. It consists of a thick fl t glass, with smooth front 
and serrated back, shown in section Fig. 72. a and b, the front and back of the 
mounting, are bolted together with the glass and packing, shown by thick lines, 
between them. The serrations, when clean, cause the water to appear black., 
as in Fig. 72a. 



Ques. 287. — For what purpose is a steam-gauge 
attached to a boiler? 

Ans. — For the purpose of indicating the number of 
pounds pressure per square inch in the boiler. 



108 



QUESTIONS AND ANSWERS 



Ques. 288. — What type of steam-gauge is in most 
general use? 

Ans. — The Bourdon spring tube gauge. 

Ques. 289. — Describe the construction of this gaug^ 
and the principle upon which it operates? 

Ans. — The Bourdon gauge consists of a thin, curved, 




FaG. 73. Auxiliary Spring Pressure Gauge. 

flattened metallic tube closed at both ends and connected 
to the steam-space of the boiler by a small pipe bent at 
some portion of its length into a curve or circle that 
becomes filled with water of condensation, and thus pre- 
vents the live steam from coming directly in contact with 
the tube or spring, while at the same time the full 



BOILER SETTINGS AND APPURTENANCES 



109 



pressure of steam in the boiler acts upon the tube, tending 
to straighten it. The end or ends of the spring tube 
being free to move, and connected by a suitable geared 
rack and pinion with the pointer of the gauge, causes it 




Fig. 74. Auxiliary Spring Pressure; Gauge, Section ai« View. 

to move across the face of the dial, thus indicating the 
pressure of the steam in pounds per square inch on the 
inner surface of the boiler. When there is no pressure 
n the boiler the pointer shouJd stand at ()• 



110 



QUESTIONS AND ANSWERS 



Ques. 290. — How should steam-gauges be cared for? 

Ans. — They should be tested frequently by comparing 
them with a gauge that has been tested against a column 
of mercur}'. 

Ques. 291. — How should the steam-space of the boiler 
be connected to the main steam-pipe or header? 

Ans. — There should be a steam stop-valve placed in the 
connection between the boiler and the header. The valve 







Fig. 75. Sectional View American Pressure Gauge. 



used for this purpose is usually an angle-valve, and 
should be constructed so as to close automatically, 
especially in a battery of two or more boilers. 

Ques. 292. — Why should this valve be self-closing in 
case the pressure in the header is higher than the pressure 
in the boiler? 

Ans. — In order that in case of an accident to one of a 
battery of boilers the steam may be prevented from pass- 
ing out of the neader and into the disabled boiler. 



BOILER SETTINGS AND APPURTENANCES 



111 



Ques. 293. — Describe the construction and operation 
of an automatic steam stop-valve. 

Ans. — The valve is opened and closed by means of a 
screw-stem passing out through the stuffing box, and 
fitted with a hand-wheel outside. In large-size valves this 
screw-thread is carried in a strong yoke outside the cas- 
ing. The pressure from the boiler is on the under side of 

the valve-disk, thus tending 
to open it. The stem or 
spindle is independent of the 
valve, and is hollow to allow 
a smaller size sliding spin- 
dle connected to the valve 
to pass into it. This spin- 
dle serves to guide and hold 
the valve steady, while at 
the same time the valve is 
free to close automatically 
any time that the pressure 
in the main exceeds the 
pressure in the boiler. 

Ques. 294. — How is the 
steam admitted to the 




Fig. 76. 



Section oe an Angle 
Stop- Valve. 



whistle or the steam siren? 

Ans. — Through a special stop-valve, usually of the 
self-closing type, being worked by a spring on the valve. 

Ques. 295. — Describe the action of the steam whistle. 

Ans. — The steam whistle produces its sound by the 
vibrations of a thin stationary metallic cylinder, under 
the impact of the steam. 



112 



QUESTIONS AND ANSWERS 



Ques. 296. — How does the steam siren produce its 
sound? 

Ans. — By means of the rotations of a small slotted 
wheel which in turning opens and closes narrow slots in 
the casing. 

Ques. 297. — How may the 
passage of water from the 
boiler into the steam-pipe be 
prevented to a large extent? 

Ans. — By means of an in- 
ternal pipe-extension called a 
dry pipe, that collects the 
steam from all parts of the 
steam-space through narrow 
slots on its upper side. The 
shape of these slots has a 
straining action on the steam. 

Ques. 298.— What is the 
object in equipping a boiler 
with a surface blow-off? 

Ans. — In order that it may 
catch and pass off impurities, 
such as grease, oil, and scum, 
floating on the surface of the 
water. 

Ques. 299. — Describe the construction and operation 
of the surface blow-off. 

Ans. — It is connected to the boiler near the water- 
ievel, and carries an internal pipe-extension that ends in a 
flat pan, directly below the water-line. It should be 




Fig. 77. Steam Fog- Whistle. 



BOILER SETTINGS AND APPURTENANCES 



113 



opened quite frequently, especially when muddy water is 
being fed to the boiler. This will allow the accumulated 
scum to pass out. 




Fig. 78. Section of a Steam Siren. 

Ques. 300. — Where and how should the bottom blow- 
off be connected? 

Ans. — The bottom blow-off should be connected to 
the lowest section of the boiler, and should be fitted with 



iI4 



QUESTIONS AND ANSWERS 






► ruvfffAn 



:: 

Lie 



30 



a straight-way valve, or a cock, in order that there may 
be no obstruction to the free passage of the mud and other 
sediment when the boiler is being cleaned. 

Ques. 301. — For what purpose is the hydrometer-cock, 
and where is it located? 

Ans. — In the marine serv- 
ice the water used in the 
boilers is more or less impreg- 
nated with solid matter, and it 
becomes necessary to test the 
density of the water in the 
boilers at certain intervals. 
The hydrometer- cock is for the 
purpose of drawing off a 
quantity of water from the 
I boiler for testing, and is fitted 
to the water-space of the 
boiler. 

Ques. 302. — Describe the 
construction and use of the 
hydrometer. 

Ans. — It is an instrument 
having a long, slender stem, 
made of either glass or metal. 
There are two bulbs in the stem. The smaller one is 
loaded and the larger one is hollow and filled with air, 
which gives the instrument buoyancy, and keeps it in a 
vertical position. The stem is graduated in degrees, each 
degree representing the presence of one-tenth the solid 




Fig. 79. Hydrometer. 



mutter in sea-water. 



BOILER SETTINGS AND APPURTENANCES 115 

Ques. 303. — What prooortion of sea-water is solid 

atter? 

Ans. — One thirty-second part. 

Ques. 304. — Upon what principle are the readings 
aken from the hydrometer based? 

Ans. — Upon the principle that when any body floats 
reely, the weight of the liquid displaced is equal to the 
weight of the body floating, so that the higher the density 
)f the liquid the less depth will the body sink in it. If the 
nstrument sinks only to the zero mark on the scale, the 
vater is fresh: if it sinks to 10 degrees, it indicates the 
presence of one-thirty-second part of solid matter, and 
f it sinks to 40 degrees, it indicates a density caused by 
he presence of four times as much solid matter as there 
s in sea-water. 

Ques. 305. — How is the water in the boiler tested 
with the hydrometer? 

Ans, — A quantity of water is drawn off through the 
ydrometer-cock, fitted for this purpose into a long pot, 
into which the instrument is inserted. 

Ques. 306. — How are boiler hydrometers graduated, 
with reference to temperature? 

Ans. — They are usually graduated to suit a tempera- 
ture of 200 degrees Fahrenheit, as that is about the temp- 
erature of the water a few seconds after being drawn off 
for testing. 

Ques. 307. — How are the expansion and contraction 
of steam-pipes provided for? 

Ans. — In the smaller sized pipes a bend can be put in 
the length of pipe that will answer the purpose, but in the 



110 



QUESTIONS AND ANSWERS 



large pipes an expansion joint, having a stuffing box foi 
the pipe to slide in and out of the adjacent pipe is fitted, 

Ques. 308.— Why is il 
necessary to place a sepa 
rator in the line of pip< 
leading from the boiler i 
the engine? 

Ans. — The object of a 
separator is to provide an 
additional safeguard against 
priming, by preventing any 
water in the steam-pipe 
from entering the cylinder. 
Ques. 309. —Describe 
the ordinary separator. 

Ans. — It is a metal cyl- 
inder larger in diameter 
than the steam-pipe, and 
connected to the pipe near 
the engine, by flange con- 
nections in such a manner 
that the larger portion of 
the separator hangs in a 
vertical position below the 
pipe. It is divided from the 
top nearly to the bottom by 
a diaphragm, and the steam 
Fig. 80. Expansion Joint. enters on one side, near to 

the top, and impinges against the diaphragm, passes 
underneath it. and out on the other side near the top. 




ggg ^^ 



BOILER SETTINGS AND APPURTENANCES 



11? 




Any water that reaches the separator is mostly left 
at the bottom, only the steam passing on to the engine 
cylinder. A valve is provided at the bottom of the 

eparator for drawing off the water. The height of the 
water in the separator is shown by a glass gauge. 

Ques. 310. — Describe the automatic steam separator. 
Ans. — In addition to the 
isual diaphragm, it is fitted 
vith an automatic blow-out 

pparatus, having a float that 
s raised as the water accumu- 
ates, and which by a system 

f levers opens a valve of 
arge area for drainage. The 

utomatic separation also has 

hand blow-off valve. 
Ques. 311. — What is an 

sbestos-packed cock, and 
vhere is it used? 

Ans. — An asbestos-packed 

ock has its top and bottom 

lands packed with asbestos, 

yhile the shell also has longi- 

udinal grooves found in it which are packed with 

sbestos. These cocks are very suitable to use on boilers 

nd steam piping where high pressures are carried, and 

t locations where cocks are more convenient than valves 

rould be. 
Ques. 312. — What are funnel dampers, and for what 

urpose are they attached? 




Fig. 81. Separator. 



118 



QUESTIONS AXD ANSWEH? 



Ans. — They are hinged dampers fitted in the uptakes 
leading from the boilers to the funnel, in order that each 



'SlEMOVTLEr 



G/sc"f#c* 







• . x 




, » 




^ « 


£ 


% • 


i 




2> 




* 


1 




• | 




1 ^^^^ 



mm wr 







•DftAtM 

Fig. 82. Automatic Separator. 



boiler may be shut off from the draught when not in use, 
and they are also for use when the fires are being cleaned 



BOILER SETTINGS AND APPURTENANCES 



119 



These dampers should be fitted so that there are no means 
of closing them permanently, but that if released they will 
at once assume the open position. 

Ques. 313. — What are funnel stays? 

Ans. — Wire ropes carried from the top of the funnel 
to the ship's sides, and fitted with adjusting screws for 
the purpose of regulating the strains. 




Fig, 83. Asbestos-Packed Cock. 

Ques. 314. — What precautions should be taken with 
these stays before raising steam in the boilers? 

Ans. — The adjusting screws should be slackened in 
order to allow for the expansion in the length of the funnel 
as it becomes heated. 

Ques. 315. — What is the usual height of the funnels of 
modern vessels? 

Ans. — Ninety to 100 feet, measured f rom the furnaces. 



120 



QUESTIONS AND ANSWERS 




^ 






A 



/ 




I I 

ZOUBLt BOTTOM 
i i 



Fig. 84. Section of Armored Cruiser, Showing Stoke-hold 
and Funnels. 



BOILEP SETTINGS AND / PPURTENANCES 



121 



Ques. 316- — For what purpose is the funnel cover? 
Ans.— It is fitted over the top of the funnel for use 




Fie. 85. Section of Armored Cruiser, Showing 
Air Screen and Coai, Bunker. 



122 QUESTIONS AND ANSWERS 

when the ship is in harbor, or if any of the funnels are not 
in use, in order to prevent rain-water from entering and 
corroding the uptakes. These covers are kept a little 
above the top of the funnel, in order to allow sufficient 
space for the escape of smoke from small fires used for 
airing and warming the boilers while they are lying 
idle. 

Ques. 317. — How is the stoke-hold of a steamer 
ventilated? 

Ans. — When natural draught only is used, screens 
are required to keep the downward current of cool air 
separate from the upward current of warm or vitiated 
air, otherwise the circulation will not be as good as it 
should be. 

Ques. 318. — When forced draught is employed for the 
furnaces, how is the air supplied? 

Ans. — One of the oldest and at the same time most 
expensive methods is to admit a jet of high-pressure 
steam directly from the boilers to the base of the funnel. 
This is known as the steam blast. Another plan of 
using the steam blast is to admit small jets of steam into 
the furnace, over the fire. 

Ques. 319. — What other principal plans for creating 
forced draught are employed? 

Ans. — First, admitting jets of compressed air into the 
base of the funnel, in a manner similar to the steam- jet; 
second, fitting a centrifugal fan in the uptake; third, 
blowing the air into closed ash-pits; fourth, closing the 
stoke-hold and keeping it filled with slightly compressed 
air. 



^ 



BOILER SETTINGS AND APPURTENANCES 



123 



Ques. 320. — Of the plans iust mentioned, which one is 
probably the most efficient? 

Ans. — Closed stoke-holds, although the third plan, 
viz., blowing the air into closed ash-pits, is an efficient 
method, but a certain degree of danger attaches to it, on 
account of the pressure in the furnaces being greater 




Fig. 86. Cross Section of Stoke-hoed, Showing Air Lock. 



than that in the stoke-hold, and unless proper precautions 
re taken before opening the furnace doors for the pur- 
pose of replenishing the fires, the flames may be blown 
nto the stoke-hold and serious results follow. 

Ques. 321. — Is this latter system of closed ash-pits 
much in vogue? 



124 



QUESTIONS AND ANSWERS 



Ans. — It is used to a large extent in the United States 
navy, also many ships of the mercantile marine service. 
The British and other navies also use it to some extent. 

Ques. 322. — How may this system of creating a forced 
draught be made safe, so as to guard against the flame 
being Mown into the stoke-hold? 




Fig. 87. Elevation of Stoke-hold, Showing Air Lock. 

Ans. — By fitting a device that automatically closes 
the air-supply to the ash-pit when the furnace door is 
opened for firing. 

Ques. 323. — What is the object of providing air-locks 
in the hold of a vessel? 



BOILER SETTINGS AND APPURTENANCES 



125 



Ans. — In order to provide for passage to and from 
he stoke-holds, when under pressure. 

Ques. 324. — Describe the construction and operation 
f an air-lock? 

Ans. — An air-lock consists of a small air-tight cham- 
>er fitted with two hinged doors opening against the air 




WATER LINC 



Fig. 88. See's Ash Ejector. 

In this apparatus, which is fitted in many large passenger steamers in which 
ie raising of ashes on deck is objectionable, the ashes are placed in a trough 
jading to a pipe, a jet of water at a pressure of about 200 pounds per square inch 
rom one of the pumps is then admitted, and scours the ashes along the pipe into 
ie sea. A small valve is fitted to permit the entry of air into the pipe during 
ie discharge. The apparatus is simple and efficient. 



126 



QUESTIONS AND ANSWERS 



pressure. In passing through only one door is open at a 
time which makes it possible to enter or leave the stoke- 
hold without allowing much air to escape and thus reduce 
the air-pressure in the stoke-hold. 

Ques. 325. — At what places aboard a ship are air-locks 
necessary? 



"STK 



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7T 



T- 



BpT' yij^^JUL— j^-jLJL— -Q=J^ 



CZD C=) (=> CZD 1=1 C= □ □ 1= C= EZ1 □ C= □ □□ 



F rrf : 



i — I o 
i — i cm 



Cm Cm 
Cm Cm 

cm cm 




cmi r— i 



^SJ 



Fig. &>. Shaking Grates. 

Ans. — At all places where communication is had 
between the compartments under pressure and any other 
part of the ship. 

Ques. 326. — What are the advantages in general 
possessed by closed stoke-holds over other systems? 

Ans. — First, a reduction in the space and weight 



BOILER SETTINGS AND APPURTENANCES 1B7 

equired by the boilers, since, by the addition of fans and 
creens, which are light and inexpensive, and supply the 
lecessary air under pressure to the furnaces, the boilers 
nay be made to develop from 20 to 25 per cent more 
)ower, than they would with natural draught; second, by 
he employment of blowing fans, a continuous supply of 
resh air in the stoke-hold is assured and the health and 
omfort of the men working there is much better provided 
or than it would be with natural draught. 

Ques. 327. — How are the ashes raised from the stoke- 
?<*ld to the deck, to be thrown overboard? 

Ans. — By means of the ash-tube and engine; the ash* 
ube leading from stoke-hold to deck, and the engine 
aising the ashes in an ash-bucket, that passes through 
he tube. Another method is by means of the ash-ejector, 
vhich is simply an inclined tube running from the stoke* 
eld to above the water-line, and overboard. At the 
ower end of this tube is a hopper, into which the ashes 
re shoveled, and at the bottom of this hopper they are 
icked up by a jet of water of high velocity, and forced 
trough the inclined tube overboard. 



CHAPTER v 

BOILER OPERATION 

Ques. 328. — What should be the first cart of an 
engineer, or water-tender, when he goes on watch? 

Ans. — He should ascertain the exact height of th< 
water in his boilers by opening the valve in each of th< 
drain-pipes of the water-columns, allowing it to blow ou 
freely for a few seconds, then closing it tight, and allowinj 
the water to settle back in the glass. 

Ques. 329. — What is one of the important dut es o 
the firemen coming off watch? 

Ans. — They should have the fires clean, the ash-pit 
all cleaned out, a good supply of coal on the floor, anc 
everything in good condition for the oncoming force. 

Ques. 330. — What implements are needed for success 
fully and quickly cleaning a fire? 

Ans. — A slice-bar, a fire-hook, a heavy iron or stee 
hoe, and a lighter hoe for cleaning the ash-pit. 

Ques. 331. — How may these tools be made, so tha 
they will be light and easy to handle and at the sam 
time strong and durable? 

Ans. — After the working ends have been fashioned t< 
the desired shape, let each be welded to a bar of 1-inch o 
1 Ms -inch round iron 10 or 12 inches in length. Thci 
take pieces of 1-inch or 1/4-inch iron pipe, cut to th< 
length desired for the handles, and weld the shanks of th< 
tools to one end of the pipe handles and to the other en< 

129 



_ 



BOILER OPERATION 129 

weld a ring handle or a short cross-bar to facilitate hand- 
ling the tools. 

Ques. 332. — When a fire shows signs of being foul 
and choked, what should be done at once? 

Ans. — Prepare to clean it by allowing one side to burn 
as low as possible, putting fresh coal on the other side 
alone. 

Ques. 333. — Describe the process of cleaning a fire. 

Ans. — When the first side has burned as low as it can, 
without danger of letting the steam-pressure drop too low, 
take the slice-bar and shove it in along the side of the fur- 
nace, on top of the clinker, and back to near the bridge- 
wall, then, using the door-jamb as a fulcrum, give it a 
quick, strong sweep across the fire, and the greater 
portion of the live coals will be pushed over to the other 
side. What remains of the coal not yet consumed can be 
pulled out upon the floor with the light hoe and shoveled 
to one side, to be thrown back into the furnace after the 
clinker is removed. Having thus disposed of the live 
coal, take the slice-bar and shove it in on top of the 
grates, under the clinker, loosening and breaking it up, 
after which take the heavy hoe and pull it all out upon 
the floor, where the intense heat contained in the clinker 
should be quenched by a helper, with a pail of water, or 
water discharged from a small rubber hose. 

Ques. 334. — Having gotten one side of the fire cleaned, 
what is the next move? 

Ans. — Close the door for that side, and with the slice 
bar in the other side, push all the liw coal over to the side 
just cleaned, where it should be leveled off, and fresh coal 



130 QUESTIONS AND ANSWERS 

added. After this has become ignited treat the other 
side in the same manner. 

Ques. 335. — Can a definite code of rules for hand firing, 
be laid down, that will suit all conditions? 

Ans. — No; owing to the fact that there are so many 
different varieties of coal, some of which need very little 
stirring or slicing, while others, that have a tendency to 
coke and form a crust on top of the fire, need to be sliced 
quite often. 

Ques. 336. — Mention a few general maxims that are 
applicable to all boiler-rooms. 

Ans. — First, keep a clean fire; second, see that every 
square inch of grate surface is covered with a good live 
fire; third, keep as level a fire as possible; fourth, when 
cleaning the fire, be sure to clear all the clinkers and dead 
ashes away from the back end of the grates at the bridge- 
wall. 

Ques. 337. — Why should the face of the bridge-wall, 
especially, be kept clean and free from ashes and clinker? 

Ans. — For the reason that this is one of the best 
points in the furnace for securing good combustion, 
provided that the bridge-wall is kept clean from the grates 
up, and by keeping the back ends of the grates clean, the 
air is allowed a free passage through them and is per- 
mitted to come directly in contact with the hot fire-brick, 
and thus one of the greatest aids to good combustion is 
utilized. 

Ques. 338. — In firing bituminous coal, what is a good 
plan to pursue in regard to the fire-doors, with some 
types of boilers? 



BOILER OPERATION 131 

Ans. — They should be left slightly ^pen for a few 
seconds, immediately after throwing in a fresh fire. 

Ques. 339. — Give the reason for doing this. 

Ans. — Bituminous coal contains a large percentage of 
volatile (light or gaseous) matter, which flashes into 
flame the instant it comes in contact with the live fire in 
the furnace, and if a sufficient supply of oxygen is not 
present just at this particular time, the combustion w r ill 
be imperfect, and the result will be the formation of 
carbon monoxide, or carbonic oxide gas, and the loss of 
about two-thirds of the heat units contained in the coal. 

Ques. 340. — How may this great loss of heat be 
guarded against, in a great measure? 

Ans. — By admitting a sufficient volume of air, either 
through the fire-doors, directly after putting in a fresh 
fire, or what is still better, providing air-ducts through 
the bridge-wall, or side walls, which will bring the air 
in above the fire. 

Ques. 341. — What quantity of air is required for the 
complete combustion of 1 pound of coal? 

Ans. — By weight, 12 pounds; by volume, about 150 
cubic feet. 

Ques. 342. — Is there any advantage gained by heating 
this air before admitting it to the furnace? 

Ans. — There is a great advantage, provided the 
heat used for this purpose would otherwise be wasted. 
Great economy in fuel, and much better combustion, 
result from supplying heated air to the furnaces. 

Ques. 343. — Describe the Howden draught system, as 
used in the marine service. 



182 



QUESTIONS AND ANSWERS 



Ans. — There is a nest of tubes in the uptake that is 
enveloped by the hot gases on their way to the stack. 
The air is caused to pass through these tubes by a 



■» — >. 



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A- 



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J£l 



J3= 



4 



v\ 



/ 



/ 



N 



• 6 boo 
poooo 
boooo 
poooo 

JOOOO 

poooo 
poooo 

— kOGOO 

poooo 

)0000 

>oooo 

)OOOC 

o.ooc 
oooo 




ooooooooooo 

oooooooooooo 

oooooooooooo 

oooooooooooo 

oooooooooooo 

ooooooooooooo 

oo ooooooooooo 

•ooooooooo oooo 

ooooooooooooo 

ooooooooooooo, 




// 




h 



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Vu^ 



Fig. 90. Arrangement of the Howden Draught System. 

blower-fan, and as a consequence is heated to a higb 
degree before passing into the ash-pit. Some of this hot 
air is also directed into the furnace above the fire, thus 
securing a good combustion of the fuel. 



_ 



BOILER OPERATION 



13a 



Ques. 344. —What precautions should be taken regard- 
ing cleanliness of the tubes? 

Ans. — The tubes of all boilers shoula ce kept clean 
and free from soot, and especially does this apply to fire- 




Fig. 91. Air Heater oe the Howden Draught System. 

tube boilers, for the reason that, when these tubes become 
clogged with soot, the efficiency of the draught is 
destroyed and the steaming capacity of the boiler is 
greatly reduced, because soot not only stops the draught 
but it is also a non-conductor of heat. 



134 QUESTIONS AND ANSWERS 

Ques. 345. — What methods are ordinarily employed 
for cleaning the soot and dust from tubes? 

Ans. — First, the steam jet, if properly made and 
connected by steam hose so as to get dry steam of high 
pressure, will do very effective work; second, a scraper 
having steel blades expanded by springs so as to fit the 
inside of the tubes snugly, should be pushed through each 
tube once or twice during each twenty-four hours of 
service. This will cut the soot loose from the inside sur- 
face of the tubes, and greatly facilitate blowing it out 
with the steam jet. For the tubes of water-tube boilers 




Fig. 92. Scraper for Cleaning Fire Tubes. 

the steam jet may be employed to advantage in cleaning 
the outside surfaces, and a rotary scraper driven by a 
small steam turbine is used for cleaning the scale forma- 
tion from the inside. 

Ques. 346. — How often should a boiler be washed out 
and cleaned inside? 

Ans. — If the feed-water is impregnated to a consider- 
able extent with scale-forming matter, the boiler should 
be washed out every two weeks, and if the water is very 
bad, the time should be shortened to one week. 

Ques. 347. — How should a boiler be prepared for 
washing out? 



BOILER OPERATION 135 

Ans. — The fire should be allowed to burn as low as 
possible, and then be all pulled out of the furnace, the 
fire-doors left slightly ajar, and the dampers left wide 
open in order that the boiler may gradually cool. 

Ques. 348. — Should a boiler be blown out, that is, 
emptied of water, while there is any steam-pressure in it? 

Ans. — It should not. 

Ques. 349.— Why not? 

Ans. — For the reason that the sudden change of 
temperature from hot to cold has an injurious effect on 
the seams and braces. It is as bad a practice to cool a 
boiler down too suddenly as it is to fire it up too quickly. 




Fig. 93. Turbine Cleaner for Water Tubes. 

Ques. 350. — What effect does the too sudden contrac- 
tion or expansion of the boiler-plates have upon the 
riveted seams? 

Ans. — Leaks are created, and very often small cracks 
radiating from the rivet-holes are started, and these 
becoming larger with each change of temperature, will 
finally destroy the strength of the seam and serious 
results will follow. 

Ques. 351. — Suppose that all of the fire has been 
pulled from the furnace and that the boiler has stood 
until the steam-gauge indicates 20 pounds pressure, 



136 QUESTIONS AND ANSWERS 

would it then be safe to blow a!l of the water out of the 
boiler? 

Ans. — It would not, for the reason that the tempera- 
ture of steam at 20 pounds pressure is 260 degrees 
Fahrenheit, and it may be assumed that the temperature 
of the metal of the boiler is at or near this temperature 
also. Assuming the temperature of the atmosphere in 
the boiler-room to be 60 degrees Fahrenheit there will be a 
range of 260 degrees — 60 degrees = 200 degrees Fahren- 
heit temperature for the boiler to pass through within a 
short time, which will certainly have a bad effect, and 
besides this, the boiler shell will be so hot that the loose 
mud and sediment left after the water has run out is 
liable to become baked upon the bottom sheets, making 
it much harder to remove. 

Ques. £c2. — Under what conditions is it best to empty 
a boiler of water preparatory to washing it out? 

Ans. — After the boiler has become comparatively cool 
and there is no pressure indicated by the steam-gauge, 
the blow-off cock may be opened and the water allowed 
to run out. The gauge-cocks and drip-valve to the 
water-column should be left open to allow the air to enter 
and displace the water, otherwise there will be a partial 
vacuum formed in the boiler, and the water will not run 
out freely. 

Ques. 353. — Mention some of the important duties of 
the boiler-washer. 

Ans. — After the water has all run out and the boiler 
has cooled sufficiently to permit it, he should go inside 
(provided there is a man-hole) and after having thoroughly 



BOILER OPERATION t37 

cleaned the inside of the boiler, he should closely examine 
all of the braces and stays, and if any are found loose or 
broken, they should be repaired at once, before the boiler 
is put in service again. The soundness of braces, rivets, 
etc., can be ascertained by tapping them with a light 
hammer. 

Ques. 354. — What should be done with the tubes of 
fire-tube boilers when they become coated with scale on 
their outside surfaces? 

Ans. — The boiler should be taken out of service, laid 
up temporarily, and the tubes taken out, cleaned, and 
those that are not corroded or pitted too badly may be 
made almost as good as new by cutting off 8 or 10 inches 
of the ends and welding pieces of new tubing on, to bring 
the tubes back to their original length, after which they 
may be put back in the boiler and be good for a long term 
of service. While the tubes are out of the boiler for re- 
pairs the boiler-washer will have a good opportunity to get 
inside and clean and inspect every portion of the inside. 

Ques. 355. — What precautions should be taken when 
connecting a recently fired-up boiler with the steam main 
or header? 

Ans. — First, the steam in the boiler to be connected 
should be raised to the same pressure as that in the main, 
then the dampers should be closed and the steam stop- 
valve should be opened slightly, just enough to permit a 
amall jet of steam to pass through, which can be heard 
by placing the ear near the body of the valve. This jet 
of steam may be passing from the main into the newly 
connected boiler, or vice versa. Whichever way it is 




Fig. 94. Square Open Heater. 



BOILER OPERATION 



139 



going, the valve ought not to be opened any farther until 
the flow of steam stops. This will indicate that the pres- 
sure has been equalized be- 
tween the boiler and the main, 
and it will then be found that 
the valve will move much 
easier, and it may be gradually 
opened until it is wide open. 

Ques. 356.— Should cold 
feed-water ever be pumped 
into a boiler that is under 
steam? 

Ans. — It should not, if it is 
possible to prevent it. 

Ques. 357. — How may the 
feed-water be heated econo- 
mically? 

Ans. — By passing it 
through a feed-heater in which 
the heating agent employed is 
the exhaust steam from the 
engines. 

Ques. 358. — How should the feed-water be supplied 
to a boiler while the boiler is being fired? 

Ans. — It should be supplied just as fast as it is evap- 
orated. The firing can then be even and regular. 

Ques. 359. — If the supply of feed-water should sud- 
denly be cut off owing to breakage of the pump or some 
other cause, and no other source of supply was available, 
what should be done? 




Fig. 95. Interior View OF 
Open Heater. 



140 



QUESTIONS AND ANSWERS 



Ans. — The dampers should be closed immediately, and 
all of the draught stopped. The fires should be deadened 
by shoveling wet or damp ashes in on top of them, or if 
ashes can not readily be procured, bank the fires over with 

green coal broken into fine 
bits. This, with the draught 
all shut off, will keep the fires 
dead, and if repairs to the 
feed-supply can not be made 
within a short time, the fires 
should be pulled, that is, if 
they have become deadened 
sufficiently. 

Ques. 360.— Should the 
fires be pulled while they are 
burning lively? 

Ans. — No; because the 
stirring will only serve to 
increase the heat, and the dan- 
ger will be aggravated. 

Ques. 361.— What is the 
primary object of making 
evaporation tests of boilers? 

Ans. — To ascertain how 
many pounds of water per 
pound of coal the boiler is evaporating. 

Ques. 362. — What other important details relating 
to the operation of the boilers may be ascertained through 
« Veil-conducted evaporation test? 

Ans. — First, the efficiency of the boiler and furnace as 




tfic 96. Baragwanath Steam 
Jacket Feed Water Heater. 



BOILER OPERATION 



141 



an apparatus for the consumption ni fuel and the evap- 
oration of water; second, the relative value of different 
varieties of coal, and 
other fuels, as heat- 
producers; third, 
whether the boilers, as 
they are operated un- 
der ordinary every- 
day conditions, are 
being operated as 
economically as they 
should be; fourth, in 
case the boilers, owing 
to an increased de- 
mand for steam, fail 
to supply a sufficient 
quantity, whether or 
not additional boilers 
are needed, or whether 
the trouble could be 
overcome by a change 
of conditions in the op- 
eration of the boilers. 

Ques. 363.— What 
are the principal data 
to be noted down dur- 
ing the progress of an 
evaporation test? 

Ans.— First, time— the number of hours that the test 
is conducted; second, the kind of coal burned; third. 




Fig 97. Closed Feed Water Heateb. 



142 QUESTIONS AND ANSWERS 

weight of coal consumed; fourth, weight of water evap- 
orated during the test; fifth, weight of dry ash returned; 
sixth, moisture in the coal per cent, seventh, dry coal 
corrected for moisture- eighth, weight of combustible; 
ninth, moisture in the steam, per cent; tenth, water 
corrected for moisture in the steam, eleventh, average 
temperature of the feed -water; twelfth, average tempera 
ture of the escaping gases; thirteenth, square feet of 
grate surface; fourteenth, square feet of heating sur- 
face; fifteenth, ratio of grate surface to heating surface. 

Ques. 3G4. — How may the weight of the coal consumed 
during the test be ascertained? 

Ans. — By having a small platform scales fitted with 
a wooden platform large enough to accommodate a wheel- 
barrow, or, in lieu of a barrow, a box large enough to 
contain two or three hundred pounds of coal. Each 
wheel-barrow load, or boxful of coal that goes to the 
boiler undei test can then be weighed and the figures be 
placed upon a tally-sheet and added together at the close 
of the test, thus giving the total weight of coal consumed 
during the test. If, at the close of the test, there is any 
of the weighed coal left on the floor, it should be weighed 
back and deducted from the total weight. 

Ques. 3G5. — How may the weight of water evaporated 
during the test be ascertained? 

Ans. — By having a hot-water meter fitted in the branch 
feed-pipe leading to the boiler under test, or if this is not 
to be had, a substitute equally as accurate can be made 
by placing two small water-tanks, each having a capacity 
of 8 or 10 cubic feet, in the vicinity of the feed-pump. 



BfJILEK OPERATION 



143 



These tanks can be made of light tank-iron, and each 
should be fitted with a nipple and valve, near the bottom, 
for connection with the suction side of the feed-pump. 
The tops of the tanks may be left open. A pipe leading 
from the main water-supply, with a branch to each tank, 
is also needed for filling them. If an open feed-water 
heater is used, and it is possible to place the tanks low 
enough to allow a portion of the hot water from the 



F£:e f^WRT£ H SUPp L y 




TOFEEPPUMP 



Fig. 98. 



heater to be led into them by gravity, it will be desirable 
to do so. If this can not be done, some other provision 
should be made for at least partially warming the water 
before it goes to the boiler. The exact capacity of each 
one of these two tanks, either in cubic feet or in pounds 
of water, should be ascertained, and then all of the feed- 
water that is supplied to the boiler during the test is to be 
first passed through the tanks, which should be numbered 



144 



QUESTIONS AND ANSWERS 



one and two respectively, in order to prevent confusion in 
keeping a record of the number of tanksfull of water used 
during the test. Two tanks should be provided, in order 
that while the feed-pump is drawing the water from one, 
the other one may be filled. The feed-pump that is used 
to supply the boiler under test should have no connection 
whatever with the main feed-supply. By keeping tab of 
the number of tanksfull of water used during the test, and 

TABLE 6 

WEIGHT OF WATER AT VARIOUS TEMPERATURES 



Temper- 


Weight per 


Temper- 


Weight per 


Temper- 


Weight per 


ature 


Cubic Foot 


ature 


Cubic Foot 


ature 


Cubic Foot 


32 F. 


62.42 lbs. 


132 F. 


61.52 lbs. 


230 F. 


59.37 lbs. 


42° 


62.42 


142 


61.34 


240° 


59.IO 


52° 


62.40 


152 


61.14 


250° 


58.85 


62° 


62.36 


162 


60.94 


26o° 


58.52 


72° 


62.30 


172 


60.73 


2 70° 


58.21 


82° 


62.21 


182 


60.50 


3 00° 


57.26 


92° 


62.II 


iq2° 


60.27 


330° 


56.24 


102° 


62.OO 


202° 


60.02 


360 


55.16 


112° 


61.86 


212° 


59.76 


3QO° 


54.03 


122° 


61.70 


220° 


59-64 


420 


52.86 



multiplying this by the capacity of each tank, the total 
weight of water evaporated is ascertained. 

Ques. 3GG. — How is the weight of dry ash ascertained? 

Ans. — No water should be allowed to come in contact 
with the ashes during the test, or if it is absolutely neces- 
sary to use water, it should be used as sparingly as 
possible, and as the ashes are pulled from the furnace or 
ash-pit, they should be thrown to one side, and allowed to 
become dry, after which the weight can be ascertained by 
means of the scales that was used for weighing the coal. 



BOILER OPERATION 145 

Ques. 367. — How is the amount of moisture in the 
coal ascertained? 

Ans. — This can generally be obtained from the reports 
of the geologist of the state in which the coal was mined. 

Ques. 368. — How is the weight of dry coa! corrected 
for moisture ascertained? 

Ans. — Deduct the percentage of moisture in the coal 
from the total weight of coal consumed. 

Ques. 369. — How is the weight of combustible ascer- 
tained? 

Ans. — Deduct the weight of dry ash returned from the 
Weight of dry coal corrected for moisture. 

Ques. 370. — How is the percentage of moisture in the 
steam determined? 

Ans. — By means of an instrument called a calorimeter, 
or if such an instrument is not at hand, the condition of 
the steam as regards its dryness may be approximately 
estimated by observing its appearance as it issues from a 
pet-cock, or other small opening into the atmosphere. 
Dry, or nearly dry steam, containing about 1 per cent of 
moisture, will be transparent close to the orifice through 
which it issues, and if it is of a grayish white color it may 
be estimated to contain not over 2 per cent of moisture. 

Ques. 371. — How is water corrected for moisture in 
the steam arrived at? 

Ans. — Deduct the percentage of moisture in the steam 
from the total weight of water evaporated during the 
test. 

Ques. 372. — How is the average temperature of the 
feed- water obtained? 



146 



QUESTIONS AND ANSWERS 




Ans. — By means of a hot-water tnermometer connected 
to the feed-pipe near to the check-valve, but between it 
and the feed-pump. If the thermometer is not attached 
to the feed-pipe, the temperature of 
the water in each tank should be 
taken and noted down, during the time 
that the feed-pump is drawing from it. 
From these notations, made at regular 
intervals during the progress of the 
test, the average temperature of the 
feed-water is easily calculated. 

Ques. 373. — How is the average 
temperature of the escaping gases 
determined? 

Ans. — By readings taken at regular 
intervals from a thermometer con- 
nected in the uptake. 

Ques. 374. — What should be done 
with the boiler and furnace before be- 
ginning an evaporative test? 

Ans. — The boiler should be thor- 
oughly cleaned, both inside and out- 
side, and especially the heating sur- 
face, by scraping and blowing the soot 
out of the tubes, if it be a return-tu- 
bular boiler, and blowing the soot and 
ashes from between the tubes if it is a 
water-tube boiler. All dust, soot, and 
ashes should be removed from the out- 
side of the shell, and also from the ^Thermometer.™ 





TOILER OPERATION 14? 

combustion chamber ana smoKe connections. The grate- 
bars and sides of the furnace should be cleared of all 
clinker, and all air-leaks made as tight as possible. 

Ques. 375. — What should be done with the water- 
connections? 

Ans. — The boiler and all of its water-connections 
should be perfectly free from leaks, especially the blow* 
off valve or cock. If any doubt exists as to the latter, it 
should be plugged, or a blind flange put on it. 

Ques. 376. — Why is it required that especial care be 
exercised regarding the water-connections? 

Ans. — For the reason that the test is made for the pur- 
pose of ascertaining the exact quantity of water that the 
toiler will evaporate with a given weight and kind of coal, 
md if any of the water fed to the boiler during the test is 
allowed to leak away, or if any water, other than that 
which has been measured by passing it through the tanks, 
is allowed to get into the boiler during the test, the results 
will be misleading and unreliable. 

Ques. 377. — Before starting the test, what other details 
regarding the boiler should be attended to carefully? 

Ans. — The boiler should be thoroughly heated, by 
having been run for several hours at the ordinary rate. 
The fire should then be cleaned and put in good condition 
to receive the fresh coal that has been weighed for the test. 

Ques. 378. — What should be done regarding the 
water-level? 

Ans. — At the time of beginning the test, the water- 
level in the boiler should be at or near the height ordi- 
narily carried, and its position should be marked by tying 



148 QUESTIONS AND ANSWERS 

a cord around one of the guard-rods of the gauge-glass 
and, to prevent any possibility of enor, the height of th< 
water in the glass should be measured in inches, and i 
memorandum made of it. 

Ques. 379. — What data regarding the steam-pressure 
should be recorded? 

Ans. — The steam-pressure as indicated by the gauge 
should be noted at the time of starting the test, and alsc 
at regular intervals during the progress of the test, ir 
order that the average pressure may be obtained. 

Ques. 380. — When should the test begin? 

Ans. — When all of the conditions just described have 
been complied with and the first lot of weighed coal ha! 
been fed to the furnace and the feed-pump is receiving 
water from one of the measuring tanks, the time shoulc 
be noted and recorded as the starting time. 

Ques. 381. — What length of time should an evapora- 
tion-test be conducted? 

Ans. — Ten houis, if it is possible to continue it that 
long. 

Ques. 382. — What conditions regarding the steam- 
pressure, condition of the fire and the water-level shoulc 
prevail at the close of the test? 

Ans. — They should be as nearly as possible the same 
at the close as they were at the beginning. The water- 
level should be the same and the quantity and the condition 
of the fire, also the steam pressure. 

Ques. 383. — How may this be accomplished? 

Ans. — Only by very careful work toward the close of 
the test. 



BOILER OPERATION 149 

Ques. 384. — If any of the weighed coal is left on the 
oor at the close of the test, what should be done with it? 

Ans. — It should be weighed back and its weight 
educted from the total weight. 

Ques. 385. — If a portion of water is left in the last 
ank tallied, what disposition should be made of it? 

Ans. — It should be measured and deducted from the 
otal. 

Ques. 386. — In making a test of the efficiency of the 
oiler, what is one of the most essential conditions to be 
aken into consideration? 

Ans. — The boiler should be operated at its fullest 
apacity, from the beginning to the end of the test, and 
rrangements should be made to dispose of the steam as 
ast as it is generated. 

Ques. 387. — How may this be done? 

Ans. — If the boiler is in a battery and connected to & 
ommon header, the other boilers can be fired lighter dur- 
ng the test; but if there is but the one boiler in use, a 
vraste-steam pipe should be temporarily connected, 
hrough which the surplus steam, if there is any, can be 
ischarged into the open air, through a valve regulated 
s required. 

Ques. 388. — If the boiler under test is fed by an 
njector instead of a pump during the test, from whence 
hould the steam-supply for the injector be taken? 

Ans. — The steam for the injector should be taken 
lirectly from the boiler under test, through a well- 
>rotected pipe. The steam for the pump, if one is used, 
hould also be taken from the same source. 



150 QUESTIONS AND ANSWERS 

Ques. 389. — How should the temperature of the feed* 
water be taken when an injector is used? 

Ans. — It should be taken from the measuring tanks* 
or at least from the suction side of the injector. 

Ques. 390.— Why? 

Ans. — Because the water in passing through the 
injector receives a large quantity of heat imparted to it 
by live steam directly from the boiler, and the tempera- 
ture of the water after it leaves the injector would not be 
a true factor for use in calculating the results of the 
test. 

Ques. 391. — For obtaining reliable and economical 
results in an evaporation-test, what conditions are 
essential regarding the draught? 

Ans. — There should be a good, strong draught, which 
can be regulated by a damper, as desired. There should 
also be a draught-gauge connected to the uptake, for the 
purpose of measuring the draught. 

Ques. 392. — Why is it necessary to measure the 
draught? 

Ans. — The principal reason for measuring the draught 
is that in making comparative tests of the heating value 
of different varieties of coal, the conditions should be the 
same as near as possible in all of the tests made, and 
especially should this be the case with the draught. 
Therefore, by using a draught-gauge and measuring the 
draught during each test, there will be no uncertainty 
regarding this very important element. 

Ques. 393. — Describe the construction and operation 
cf a draught-gauge. 



BOILER OPERATION 



151 



Ans. — The usual form of drr^ght-gauge is a glass 
tube bent in the shape of the letter U. One leg i s con- 
nected to the uptake by a small rubber hose, while the 
other leg is open to the atmosphere. 

A scale marked in tenths of an inch is fitted between 
the two legs of the gauge. The 
glass tube is partly filled with water, 
which will, when there is no draught, 
stand at the same height in both 
legs, provided the instrument stands 
perpendicular, which is its normal 
position. When connected to the 
uptake, the suction caused by the 
draught will cause the water in the 
leg to which the hose is attached to 
rise, while the level of the water in 
the leg that is open to the atmos- 
phere will be equally depressed, and 
the extent of the variation in frac- 
tions of an inch is the measure of 
the draught. Thus the draught is 
referred to as being .5 .7 or .75 inch. 

Ques. 394.— What is the least 
iraught that should be used, in or- 
ler to obtain good results? 

Ans.— The draught should not be less than .5 inch. 
Better results may be obtained with a draught of .7 inch. 

Ques. 395.— If the test is made for the purpose of 
letermining the efficiency of the boiler and setting as a 
vhole, including grate, draught, etc., and also for compar- 




Fig. 100. Draught Gauge, 



152 QUESTIONS AND ANSWERS 

ing the heating qualities of different kinds of coal* what 
must the result be based upon? 

Ans. — Upon the number of pounds of water evapo- 
rated per pound of coal burned. 

Ques. 396. — What is implied in the expression "per 
pound of coal burned' ' as used in this connection? 

Ans. — It includes not only the purely combustible 
matter in the coal, but the non-combustible also, such as 
ash, moisture, etc. Some varieties of Western coal con- 
tain as high as 12 to 14 per cent of moisture, and the 
ability of the furnace to extract heat from the mass is to 
be tested, as well as the ability of the boiler to absorb and 
transmit that heat to the water. 

Ques. 397. — If the test is to determine the efficiency 
of the boiler itself as an absorber and transmitter of heat, 
what must be the factor for working out the result? 

Ans. — The weight of the combustible alone must be 
considered. 

Ques. 398. — When making a series of tests for the 
purpose of comparing the economical value of different 
kinds of coal, what conditions should prevail? 

Ans. — The conditions should be as nearly uniform as 
possible; that is, let the tests all be made under ordinary 
working conditions, and with the same boiler or boilers, 
and if possible with the same fireman. 

Ques. 399. — What is meant by the term "equivalent 
evaporation, ' ' as applied to the results of an evaporation- 
test? 

Ans. — The term "equivalent evaporation/' or t le 
evaporation from and at 212 degrees, assumes that the 



BOILER OPERATION 153 

feed-water enters the boiler at a temperature of 212 
degrees and is evaporated into steam at 212 degrees tem- 
perature, and at atmospheric pressure, as, for instance, 
if the top man-hole plate were left out, or some other 
large opening in the steam-space of the boiler allowed the 
steam to escape into the atmosphere as fast as it was 
generated. 

Ques. 400. — Why is it necessary to introduce this 
feature into calculations of the results of evaporation- 
tests? 

Ans. — Owing to the variation in the average tem- 
perature of the feed-water used in different tests, and also- 
the variation in the average steam-pressure, it is 
absolutely necessary that the results of all tests be 
brought by computation to the common basis of 
212 degrees in order to obtain a fair and just comparison. 

Ques. 401. — Describe the method of calculation by 
which this is done. 

Ans. — Suppose an evaporation-test to have been made, 
and that the average steam-pressure by the gauge was 
85 pounds, which equals 100 pounds absolute pressure, 
and that the average temperature of the feed-water was 
141 degrees. By reference to Table 1, Chapter 1, it will 
be found that in a pound (weight) of steam at 100 pounds 
absolute pressure there are 1,181.1 heat units or thermal 
units, and in a pound of water at 141 degrees temperature 
there are 109.9 heat units. It therefore required 
1,181.1 — 109.9 = 1,071.9 heat units to convert 1 pound 
of feed- water at 141 degrees temperature into steam at 
85 pounds gauge, or 100 pounds absolute pressure. Now 



154 QUESTIONS AND ANSWERS 

to convert a pound of water at 212 degrees temperature 
into steam at atmospheric pressure and 212 degrees tem- 
perature, requires (according to Table l) 965.7 heat units, 
and the 1,071.9 heat units would evaporate 1,071.9 -*- 965.7 
= 1.11 pounds of water from and at 212 degrees. The 
1.11 is the factor of evaporation for 85 pounds gauge 
pressure, and 141 degrees temperature of feed-water, 

Ques. 402. — What use is made of this factor of evap- 
oration in the calculation? 

Ans. — One of the results of the test was "weight of 
water corrected for moisture in the steam," and by mul- 
tiplying this result by the factor of evaporation, the 
"equivalent evaporation" is ascertained. 

Ques. 403. — Upon what is the factor of evaporation 
based, in any test? 

Ans. — Upon the steam-pressure and the temperature 
of the feed-water. 

Ques. 404. — Give the formula for finding this factor 
for any test. 

TT L. 

Ans. — The formula is: Factor =——,in which H = 

9bo.7 

total heat in the steam, h = total heat in the feed-water, 
and 965.7 = the number of heat units in a pound of 
steam at atmospheric pressure and 212 degrees tempera- 
ture. Table 7 gives the factor of evaporation, already 
calculated, for various pressures and temperatures. 

Ques. 405. — If it is desired to ascertain the cost of 
coal for generating the steam used for operating an engine 
that uses 30 pounds of steam per horse-power per hour, 
what is the method of calculation? 



Ans.— If the engine uses 30 pounds of steam per horse- 
ower per hour, and it has been found by the test that 
pound of the coal used would evaporate 9 pounds of 
ater into steam of the pressure at which it is supplied to 
le engine, the actual consumption of fuel by the engine 

Table 7, 
Factors of Evaporation 



BOILER OPERATION 



155 



D g 



12 
00° 

K 

82° 

73° 
6 4 ° 

52° 

43° 
34° 
25° 
13° 
04° 
95° 
86° 

77° 
65° 
56° 
47° 

38° 



&A 






I.027 
I.039 

I.049 
I.05S 
I.O67 

I.077 
I.O89 
I.099 
I. I08 
I.II8 

I.I30 
I.I38 

I.I4Q 
1.158 
1.167 
1. 180 
1. 189 

1. 199 
1.208 



CO 



1.030 
1.042 
1.052 
1. 061 
1.070 
1.080 
1.092 
1. 102 
I. Ill 

1. 121 

1. 133 
1. 142 
1. 152 
I. l6l 
1. 170 
I.183 
1. 192 
1. 20I 
1. 211 



CO 

ed 

o 



co 



CO 



CO 

Si 

<3 CO 

u 
Ph 



1.032 
I 045 
1.054 

1.064 

1.073 
1.083 

1.095 
1. 105 
1. 114 
1. 123 
1.136 
1. 145 
1.154 
1. 164 

1.173 
1.186 

1. 195 

1.204 
1. 214 



1.035 
1.047 
1.057 

1.066 
1.076 

1.085 

1.098 
1. 107 
1.116 
1. 126 

1. 138 
1.148 

1. 157 

1. 166 

1. 176 

1. 188 
1. 197 

1.207 
1. 216 



1.037 
1.050 

1.059 

1.069 

1.078 
1.087 

1. 100 
1. 109 
1. 119 

1. 128 
1. 140 
1. 150 

1. 159 
1. 169 
I.I78 

1. 190 
I.200 
I.209 

1. 218 



CO 
10 O 

a . 
O g 

CO 

u 



en 

bfl 2 

3 M 

CTj . 

Geo 
CO 

CD 

u 



V n 
bfl CN 

3 M 

a . 

Oco 
CO 

D 



1.039 
1.052 
1. 061 
1. 071 
1.080 
1.090 
1. 102 
I. Ill 

1. 121 

1. 130 
1. 143 
1.152 

1. 161 

1. 171 
1. 180 
1. 192 

1.202 

I. 211 
I.220 



I. O4I 

I.054 
I.063 
I.073 
1.082 
1. 09 1 
1. 104 

1. 113 

I.I23 

1. 132 
1. 145 
I. 154 

I. I63 

I.I73 
1. 182 

I. 194 
I.204 
1. 213 
1.222 



I.O43 
I.O56 
I.065 

I.O/5 
I.034 

I.093 
1. 106 

I.II5 
1. 125 

1. 134 
1. 146 

1. 156 
1. 165 

I.I74 

1. 1 84 
1. 196 
1.206 
1. 215 
1.224 



to %■ 



I.047 
I.059 
I.069 
I.078 
I.087 
1.097 
I. IO9 

1. 119 
1. 128 

1. 137 
1. 150 

1. 159 
1. 169 
1. 178 
1. 187 
1.200 
I.209 
1. 218 
1.228 



vould be as follows: 30 -5- 9 = 3.33 pounds of coal per 
lorse-power per hour, which, multiplied by the total horse- 
>ower developed by the engine, will give the total weight 
)f coal consumed in one hour's run. 

Ques. 406. — What is the meaning of the expression 
'boiler horse-power?' ' 



156 QUESTIONS AND ANSWERS 

Ans. — The latest decision of the American Society o 
Mechanical Engineers regarding the horse-power oi 
a boiler is "that the unit of commercia 1 horse-power de 
veloped by a boiler shall be taken as 34j/2 units of evapor« 
ation." That is, 34^2 pounds of water evaporated pel 
hour from a feed temperature of 212 degrees into steai 
of the same temperature. 

This standard is equivalent to 33,317 heat units per 
hour. It is also practically equivalent to an evaporation 
of 30 pounds of water from a feed temperature of 
100 degrees Fahrenheit into steam of 70 pounds gauge- 
pressure. 

Ques. 407. — According to this rule, what would be 
the horse-power of a boiler in which during a 10-hour 
test, the evaporation from and at 212 degrees was found 
by calculation to have been 86,250 pounds of water? 

Ans. — The horse-power developed would be 86,250 - 
10-^ 34.5 = 250 horse-power. 

Ques. 408. — In what way can the maximum economy 
in the consumption of coal be obtained? 

Ans. — There is only one way, and that is by keeping 
a continuous supply of coal on the fires and admitting a 
regular and sufficient quantity of air for its combustion, 

Ques. 409. — Can these conditions be reached by hand 
firing? 

Ans. — They can not, no matter how careful and skil- 
ful the firemen may be. 

Ques. 410. — Mention two of the principal disadvan- 
tages attending hand firing. 

Ans. — First, during the time of firing the furnace 



BOILER OPERATION J57 

door is wide open, thus admitting a large volume of cold 
air ; second, immediately after throwing in a fresh supply 
of coal, there is a sudden generation of gas, a large per- 
centage of which escapes without being entirely consumed, 
and much heat is thus wasted. 

Ques. 411.— What are the principles governing the 
operation of mechanical or automatic stokers? 

Ans. — First, a continuous supply of coal and air; 
second, thorough regulation of the supply of fuel and air, 
according to the demand upon the boilers for steam; 
third, the intermittent opening and closing of the furnace 
doors is entirely prevented. 

Ques. 412.— What are some of the disadvantages 
attending the use of mechanical stokers? 

Ans.— First, the great cost of installing them; second, 
in case of a sudden demand upon the boilers for more 
steam, the mechanical stoker can not respond as promptly 
as in hand firing; third, the extra cost for power to 
operate them. 

Ques. 413.— How many different classes of mechanical 
stokers are in use? 

Ans. — Four general classes. 

Ques. 414.— Describe the construction and operation 
)f stokers belonging to Class 1. 

Ans.— The grate consists of an endless chain of short 
>ars, that travels in a horizontal direction from the front 
o the back of the furnace, over sprocket wheels operated 
ither by a small auxiliary engine or by power derived 
rom an overhead line of shafting in front of the boilers, 
"he motion of the endless chain of grates is of course very 



158 



QUESTIONS AND ANSWERS 




I 



BOILER OPERATION 



159 



slow, but it is continuous and regular, receiving the supply 
of coal at the front and depositing the ashes at the bacK 
nd, where they drop into the ash-pit. 




o 

in 

o o 

<% 

«« 

W Q 

a 
O 



a 



Ques. 415. — What type of stokers is included iu 
[lass 2 ? 

Ans. — Stokers having grate-bars somewhat after the 
rdinary hand-fired type, but having a continuous motion 



160 



QUESTIONS AND ANSWERS 



no and down, of- forward and back. Although this 
motion is slight, it serves to keep the fuel stirred and 
loosened, thus preventing the fire from becoming sluggish 
Ques. 416. — What position do the grate-bars in 
Oass 2 occupy? 




Fig. 103. Vicars Mechanical Stoker. 



Ans. — Either horizontal, or slightly inclined, and their 
constant motion tends to gradually advance the coal from 
the front to the back end of the furnace. 

Ques. 417. — What kinds of stokers are included in 
Class 3 ? 

Ans. — Stokers in which the grates are steeply inclined. 



BOILER OPERATION 



161 



The coal is fed onto the upper ends of the gates, whicfop - 
having a slow motion, gradually force the coal forward as 
fast as required. In some stokers of this class, as, for 
instance, the Murphy, the grates incline from the sides 
towards the middle of the furnace, but in the majority of 
cases the inclination is from the front towards the back. 




Fig. 104. The Murphy Automatic Furnace. 

Ques. 418. — What is the leading feature governing the 
operation of stokers ^belonging to Class 4 ? 

Ans. — Thecoal is supplied from underneath the grates, 
and is pushed iffT through an ppening left for the purpose 
midway of the length of the furnace. The gases, on 
being distilled, come in contact immediately with the hot 
| bed of coke on top, and the result is good combustion. 

Ques. 419. — What are. stokers belonging to Class A 
I called? 



162 



QUESTIONS AND ANSWERS 



Ans. — Under-feed stokers. 

Ques. 420. — What methods are employed for forcing 
the coal up into the furnace with under-feed stokers? 




Ans. — Steam is the active agent, either by means of 
a steam-ram, or a long, slowly revolving screw, driven 
by a small engine. 



BOILER OPERATION 



163 



Ques. 421. — How is the air supplied when an under- 
feed stoker is used? 




<cq(JQft 



Ans. — Forced draught is employed, and the air is 
blown into the furnace through tuyeres. 

Ques. 422. — How is the coal supplied to mechanical 
Stokers, other than the under-feed type? 

Ans. — In two ways; either by being shoveled by hand 



164 QUESTIONS AND ANSWERS 

into hoppers in front of and above the grates, or, as is the 
case in most of the large plants using them, it is elevated 
by machinery and deposited in chutes, through which it 
is fed to each boiler by gravitv. The coal used in 
mechanical stokers is in the form of screenings or nut 
coal. 

Ques. 423. — Have mechanical stokers for feeding coal 
been applied in the marine service to any great extent? 

Ans. — They have"not, up to the present time. 




Fie. 107. Jones Under-feed Stoker, Having a Steam Ram. 

Ques. 424. — In what way is it possible to successfully 
use automatic or mechanical stokers on marine boilers? 

Ans. — By the use of liquid fuels, such as petroleum, 
blast-furnace oil, tar oil, etc. 

Ques. 425. — Of what does petroleum consist? 

Ans. — Petroleum consists practically of carbon, 
hydrogen, and oxygen, in the following proportions: 
Carbon, 85 per cent; hydrogen, 13 per cent, and oxygen, 
2 per cent. 

Ques. 426. — What is the heating value of 1 pound of 
petroleum? 



BOILER OPERATION 165 

Ans. — About 20,000 heat units, or about one-third 
more than the best coal. 

Ques. 427. — How is petroleum fed to the furnaces? 

Ans. — By being forced through nozzles having two 
or three holes, or annular spaces, from one of which the 
petroleum flows out, under pressure, while a jet of steam 
or compressed air issuing from another orifice catches 
the oil and * 'pulverizes' ' it into a fine spray, in which 
form it strikes the fire. The air for combustion Is 
admitted through a third orifice, or if not thus supplied, 




Fig. 108. Section ai« View oe Jones Under-eeed Stoker. 

the air for combustion is admitted by suitable orifices in 
the furnace front. 

Ques. 428. — How is the furnace arranged for burning 
petroleum? 

Ans. — A layer of broken fire-brick or asbestos is 
placed on the grate, and fire-brick screens, or bafflers, 
are placed in the way of the flame, thus providing a red- 
hbt surface against which it impinges. Otherwise the 
combustion would be greatly hindered by the compara- 
tively cool surfaces of the boiler-plates and tubes. 

Ques. 429.— What agent has been found to be the best 



166 



QUESTIONS AND ANSWERS 



for pulverizing the petroleum and spraying it into the 
furnace? 

Ans. — Compressed air, slightly heated. 

Ques. 430 — What is one of the disadvantages attend- 
ing the use of steam for this purpose? 

Ans. — The danger of the flame being extinguished b^ 
water that is sometimes carried over with the steam. 




=2r 



smm&ZipeB 



Fig. 109. Petroleum Burner for Boiler Furnace. 

Ques. 431. — How is the oil supplied to the nozzles? 

Ans. — By means of pumps that draw it from the 
bunkers and discharge it into a reservoir, and from 
thence it is fed to the burners. 

Ques. 432. — What are the advantages in favor of 
petroleum fuel, especially for the marine service? 

Ans. — First, superior evaporation, and, as a conse- 
quence, great reduction in the weight of fuel to be carried; 



BOILER OPERATION 167 

&( cond, less space occupied by the fuel and ease of ship- 
pi ig it into the bunkers; third, reduction of stoke-hold 
force, also less space required in the stoke-hold; fourth, 
regularity of combustion and no reduction of power, due 
to cleaning fires, they being always clean and in a good 
condition; fifth, increased durability of boilers, owing to 
the fact that there are no variations of temperature, due 
to opening fire-doors, for coaling or cleaning; sixth, 
greater control over the expenditure of fuel, consequently 
less waste of steam at the safety valves, also less danger 
of a short supply of steam in case of a sudden demand 
upon the boilers. 

Ques. 433. — What are some of the principal objections 
to its use on board of vessels? 

Ans. — First, limited supply; second, vessels proceed- 
ing on long voyages could not, with present facilities, 
replenish their bunkers when required; third, danger of 
the generation of inflammable gases; fourth in war-ships 
the risk of possible loss of the fuel, in the event of injury 
to the bunker containing it. 

Ques. 434. — Has the combination of coal and petro- 
leum, in the same furnace, ever been attempted? 

Ans. — Experiments along this line are being made in 
the British and other navies. 

Ques. 435. — How are the furnaces fitted for this 
purpose? 

Ans. — The same as for hand firing with coal, and in 
addition, a number of nozzles are placed in the front 
above the fire for injecting the petroleum over the incan- 
descent coal. 



168 QUESTIONS AND ANSWERS 

Ques. 436. — Upon what does the efficiency of a steam- 
ship, or of a manufacturing establishment in which steam 
is used for power, largely depend? 

Ans. — Upon the condition of the boilers and the care 
and labor expended for their preservation. 

Ques. 437. — What was formerly one of the most dan- 
gerous and active agents in the deterioration of boilers, 
especially in the marine service? 
' Ans. — Corrosion of the boiler-plates and stays. 

Ques. 438. — What was found, by a long series of 
experiments, to be the principal cause of this corro- 
sion? 

Ans. — The action of the fatty acids evolved by 
saponification from the heated tallow and vegetable oils, 
used at the time for the internal lubrication of the cylin- 
ders and valve-chests. 

Ques. 439. — How were these oils carried into the 
boilers? 

Ans. — In condensing systems, where the water of con- 
densation was used for feed-water, the waste oil in the 
exhaust steam mingled with the feed-water and was 
carried into the boilers. 

Ques. 440. — How has the danger from this source been 
largely obviated in late years? 

Ans. — By the use of mineral oils for internal 
lubrication. % 

*^ues. 441. — In what other way has the danger of 
corrosion been lessened? 

Ans. — By the use of mild steel instead of iron plates I 
in the construction of boilers. This steel is made by the 



BOILER OPERATION 169 

Seimens-Martin process, and is much stronger than iron 
and less liable to corrosive action. 

Ques. 442. — Of what material are marine boilers now 
made entirely? 

Ans. — Of steel, except the tubes, which are usually 
made of iron in the mercantile service. Steel tubes are 
used in war-ships. The furnaces and internal parts, that 
have to be welded or flanged, are made from specially 
soft steel plates. 

Ques. 443. — What is the principal cause of corrosion 
in boilers at the present time? 

Ans. — Oxidation of the plates, which results from 
contact with moisture and air, either carried in with the 
feed-water, or existing in the atmosphere when the boilers 
are empty. 

Ques. 444. — What conditions must exist in order that 
corrosion shall take place from this cause? 

Ans. — The simultaneous presence of both air and 
water, because neither dry air nor fresh water in which 
there is absolutely no air has any chemical action on steel 
or iron. Air dissolved in water is especially active, and 
the action is increased by the presence of various 
chlorides, such as magnesium and sodium. 

Ques. 445. — Are there any other causes that tend 
toward the corrosion of boilers, internally? 

Ans. — There are; for instance, hot sea-water, even 
when entirely deprived of air, has some action on steel 
and iron. It has been found that at the high tempera- 
tures now common in boilers, the chloride of magnesium 
contained in sea-water is decomposed by the heat and 



170 QUESTIONS AND ANSWERS 

gives off hydrochloric acid, the evolution of acid being 
accelerated with increase of density. 

Ques. 446. — Should sea-water be admitted to boilers if 
it is possible to prevent it? 

Ans. — It should not; but if a portion is used, it is 
important that sufficient alkali, preferably lime, be 
admitted with the feed-water to render the water in the 
boilers slightly alkaline by the litmus test. 

Ques. 447. — Does galvanic action, due to differences in 
the material used in the construction of the boilers, con- 
duce towards corrosion? 

Ans. — Galvanic action is probably a minor cause of 
corrosion. 

Ques. 448. — What are some of the methods that 
may be employed for the prevention of corrosion in 
boilers? 

Ans. — First, the admittance of air into the boilers 
while at work should be prevented as much as possible. 
This may be done by having a tank, called the feed-tank, 
into which the air-pump may discharge its water, and 
from which the feed-pumps can draw their water for sup- 
plying the boilers. The feed-pumps should be independent 
pumps, which can be so regulated in speed as to be 
always fully supplied with water and never to empty the 
feed-tank and so suck in and discharge air into the boilers. 
Second, the complete exclusion of sea-water from the 
boilers if possible. The waste of feed-water should be 
made good by e /aporators and a reserve of fresh water 
in tanks. Third, mineral oils, which consist of hydrocar- 
bons only, should be used exclusively for lubrication of 



BOILER OPERATION 



171 



all internal parts of the engines and pumps requiring 
lubrication. 

Ques. 449. — How may the injurious effects of galvanic 
action be neutralized? 

Ans. — By the suspension of zinc slabs in various 

parts of the boiler, both below the water-line and also in 

the steam-space. Then if there be any galvanic action 

the zinc slabs will be attacked instead of the material of 

the boiler itself. 

f 




h 



m 



ZINC;SIA0 



Fig. 110. Method of Suspending Zinc Seabs. 

Ques. 450. — What is an important point to be 
observed when placing these zinc slabs? 

Ans. — They should be in actual bright contact with 
the material of the boiler and they should be well distrib- 
uted, so that every portion of the interior surface of the 
boiler is protected. 

Ques. 451. — What is the theory of the action of these 
zinc slabs, in preventing galvanic corrosion? 



172 



QUESTIONS AND ANSWERS 



Ans. — Zinc is an electro-positive metal, and it being 
suspended in the boiler causes the steel of the boiler to 
become electro-negative and thus any corrosive agent is 
induced to attack the zinc, leaving the steel uninjured. 



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This preservative action can only take place when the 
boilers have water in them and the zinc slabs fitted in the 
Steam-space act only when the boilers are completely filled 
with water. 



CHAPTER VI 

TYPES OF ENGINES — CLASSIFICATION 

Ques. 452: — Into what three gene/al classes may 
marine and stationary engines be divided? 

Ans. — First, simple; second, compound; third, triple, 
or quadruple expansion. 

Ques. 453. — What causes the piston of a steam-engine 
to move back and forth in the cylinder? 




Fig. 112. Cross Compound Direct Connected Corliss Engine, 
Allis Chalmers Co. 

« 

Ans. — The expansive force of the steam that is 
admitted alternately behind .the piston, at either end of the 
cylinder. 

Ques. 454. — Describe the action of the steam in a 
simple engine. 

Ans. — Tn a simple engine the steam is used in but one 
cylinder, and from thence it is exhausted, either into the 
atmosphere or into a condensor. 

1"3 



174 QUESTIONS AND ANSWERS 

Ques. 455. — What is the leading characteristic of a 
compound engine? 

Ans. — In a compound engine the steam is made to do 
work in two or more cylinders befo r ^ it is allowed to 
exhaust. 

Ques. 456. — How is this accomplished? 

Ans. — The compound engine is fitted with two, and in 
some cases with three cylinders. The cylinder into which 
steam at boiler pressure is admitted is termed the h/gh- 
pressure cylinder and is the smallest of the group, in 




Fig. 11J. Tanl-em Compound Engine, Buckeye Engine Co. 

diameter. The exhaust passage (or receiver) from this 
cylinder leads directly to the valve-chest of another 
cylinder, larger in diameter, termed the low-pressure 
cylinder, and thus conducts the exhaust from the high 
to the low-pressure cylinder, w r herein it again serves as 
working steam, and if the cylinders are properly propor- 
tioned for the pressure, the amount of work done in each 
cylinder will be the same. 

Ques. 457. — How many kinds of compound engines 
are in use generally? 



TYPES OF ENGINES CLASSIFICATION 



17* 



Ans. — Two kinds: First, the cross compound, in 
which the cylinders stand parallel, eaoh having its indi- 
vidual cross-head, connecting rod, and valve-gear, and ail 
connected to a common crank-shaft; second, tandem 




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Compound, in which the cylinders are tandem to each 
other, and one piston rod, cross-head, connecting rod, and 
valve-gear is common to both, although each cylinder has 



176 



QUESTIONS AND ANSWERS 



its own valve or valves for controlling the admission and 
release of the steam. 

Ques. 458. — What is implied in the expression "triple 
expansion ?" 

Ans. — Triple expansion means that the steam has been 
allowed to expand through three successive stages, doing 





Fig. 115. Shows a Triple Ex- 
pansion Engine in which the 
Hich Pressure is Tandem with 
The Intermediate Cylinder. 



Fig. 115a. Shows the Ordinary Ar« 

RANGEMENT OF CYLINDERS FOR A TrI« 

i'le Expansion Engine. 



a fixed amount of work in each stage, before release 
occurs. 

Ques. 459. — How many cylinders are required on a 
triple-expansion engine? 

Ans. — Never less than three, and for large, high-speed 
engines it often becomes necessary to have two lowr 



TYPES OF ENGINES CLASSIFICATION 



17? 



pressure cylinders, thus making a four-cylinder triple- 
expansion engine. 

Ques. 460. — Are four cylinder triple-expansion en- 
gines much in use? 

Ans. — They are in the marine service, and especially 
in the British navy, and they are also used to a large 
extent in the mercantile service. 

Ques. 461. — Describe the action of the steam in a 
quadruple-expansion engine. 



MOMBOILBB 




ma — m — cm — mn 



Fig. 116. Arrangement of Four Cylinder Trifle Expansion Engine 

for Marine Service. 



Ans. — In a quadruple-expansion engine, the expansion 
of the steam is divided up into four stages by causing it 
to pass through four successive cylinders, termed 
respectively the high-pressure, first intermediate, second 
intermediate, and low-pressure. In some of the larger 
engines of this type there are two low-pressure cylinders,, 
thus making five cylinders in all. 

Ques. 462. — What pressures of steam are usuallv 
used in this type of engine? 



178 



QUESTIONS AND ANSWERS 



Ans. — From 200 to 250 pounds per square inch. 
Ques. 463. — What are some of the advantages that 
ire to be gained in the use of steam by stage expansion? 




TYPES OF ENGINES CLASSIFICATION 179 

Ans. — First, that the cylinder into which steam 
directly from the boiler is admitted is never open to the 
cooling influence of the atmosphere, or condensor, hence 
there is not so much cooling and condensation of the 
entering steam; second, the steam that is condensed and 
reevaporated in the first cylinder reappears as working 
steam in the second cylinder; third, the loss from con- 
densation in the second and third cylinders is also reduced, 
owing to the smaller range of temperature, between 
admission and exhaust in those cylinders. 

Ques. 464. — What are the mechanical advantages of 
compound and triple-expansion engines, for heavy duty? 

Ans. — First, the facility with which high rates of 
expansion may be carried out without bringing excessive 
strains and stresses on the framing of the engine; second, 
a greater uniformity of twisting moment on the shaft. 

Ques. 465. — What are the usual ratios of cylinder 
volumes in compound and triple and quadruple-expansion 
engines? 

Ans. — For compound engines 1 to 4 between high and 
low-pressure cylinders. For triple-expansion engines, 
the ratios are about 1, 3 and 7, for high, intermediate 
and low-pressure cylinders. For quadruple-expansion 
engines the ratios are as follows: 1, 2, 4/4 and 10/4 for 
high-pressure, first intermediate, second intermediate and 
low-pressure respectively. 

Ques. 466. — What is meant by the term receiver, a9 
used in connection with the stage-expansion of steam? 

Ans. — In the case of a compound engine the receiver 
is the whole of the space between the high-pressure 



180 



QUESTIONS AND ANSWERS 



piston, when at the end of its stroke, and the back of the 
low-pressure steam-valve, whether it be slide rotative, or 
piston-valve. In the case of a triple-expansion engine, 
the space between the piston at the end of its stroke and 
the back of the intermediate steam-valve is called the 
intermediate receiver, and the space between the inter- 




Fic. 118. Sectional View of Tandem Compound Cylinders, Showing 
Arrangement of Steam Chests and Valves. 



mediate piston at the end of its stroke and the low-pres- 
sure steam-valve is the low-pressure receiver. 

Ques. 4G7. — What is the usual volume of these 
receivers in modern practice? 

Ans. — After many experiments with large reservoirs 
as receivers, it has been found that all that is necessary 
is a comparatively large exhaust pipe from the exhaust 



TYPES OF ENGINES — CLASSIFICATION 



181 



orifice of the high-pressure cylinder to the steam inlet of 
the next lower pressure cylinder, it having been demon- 
strated that the volume of the exhaust passage and pipe 
from the high-pressure cylinder and the low-pressure 
valve-chest supplied sufficient space to allow for the com- 
pression that occurs between release from the high-pres- 
sure cylinder and admission to the low-pressure cylinder. 

Jroytitota* Q ues - 468.— Does this law 
apply in the case of triple and 
quadruple-expansion engines? 

Ans. — It does. 

Ques. 469. — Upon what 
does the power of any stage- 
expansion engine depend? 

Ans. — The power of a 
stage-expansion engine work- 
ing at any given rate of ex- 
pansion depends entirely upon 
the dimension of its low- 
pressure cylinder or cylinders, 

Fig. 119. Tandem Quadruple Ex- an( J j s not affected by the size 
pansion Marine EngineShowing j 

of its high-pressure cylinder, 
carries out but one stage in the 




Arrangement of Cylinders. 



which latter, in fact, 
expansion. 

Ques. 470. — What does the capacity of the low-pres- 
sure cylinder or cylinders of such an engine require to be? 

Ans. — The same as that of the whole of the cylinders 
of a simple engine of the same power, working at the 
same initial pressure and total ratio of expansion. 

Ques. 471.— Why is this? 



182 



QUESTIONS AND ANSWERS 



Ans. — For the reason that, since the initial pressures 
and ratios of expansion are the same in bot.i engines, it 
follows that the terminal pressures and volumes must 
also be identical in both cases. In the simple engine the 
whole of the steam at the end of the stroke fills all of the 
cylinders, while in the compound engine it is contained in 
the low-pressure cylinder or cylinders only, hence the 
capacity of this cylinder must be equal to the capacity of 
all the cylinders of the simple engine. 



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2* IP 



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PROM BOILCR 



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Fig. 119a. Quadruple Expansion Engine, with Cylinders as Ordinaril* 
Arranged — Arrows Show Course Taken by the Steam. 



Ques. 472. — Why is it necessary in some cases to 
employ two low-pressure cylinders? 

Ans. — For the reason that in very large engines one 
low-pressure cylinder would be too large and unwieldy, 
therefore it is divided into two equal parts. 

Ques. 473. — Are compound and triple-expansion 
engines much in use outside of the marine service? 

Ans. — They are to a large extent, owing to the great 
gain in economy over the simple engine. Practically all 
large manufacturing plants u c/ * them. 



TYPES OF ENGINES CLASSIFICATION 



183 



Ques. 474. — What other types of engines are in use 
in the marine service? 

Ans. — The vertical walking-beam engine is largely in 
use on the lakes, bays, and rivers of the United States, 




Fig* 120. Belleville Reducing Valvts. 



Ques. 475. — What is the leading characteristic of this 
type of engine? 

Ans. — It has usually but a single cylinder^ with a very 



184 



QUESTIONS AND ANSWERS 



long stroke in proportion to its diameter, the length of 
the stroke varying from 7 to 12 feet. 

Ques. 476. — What pressures of steam are usually 
employed in beam engines? 

Ans. — Owing to the fact that the steam is expanded 
in a single cylinder only t the pressure carried is low — 50 
to 60 pounds per square inch. 

Ques. 477. — Mention another type of engine that is in 
common use on Western rivers. 




Fig. 121. 

Fig. 121 is a sectional view of the cylinder, steam, and exhaust-chests, and 
the valve-chambers of a Corliss engine. 1 and 2 are the steam-valves and 3 and 
-4 the exhaust-valves. The valves work in cylindrical chambers accurately bored 
•ut, the face of the valve being turned off to fit steam tight. They are what is 

termed rotative valves, that is, they receive a semi-rotary motion from the wrist' 

~iate, which in turn is actuated by the eccentric. 



Ans. — The stern-wheel engine, consisting of a pair ot 
engines, one cylinder on either side of the boat, and 
directly connected to the shaft of the stern-wheel. Like 
the beam engine, the stroke is long in proportion to the 
cylinder diameter. 

Ques. 478. — Are these engines simple or compound? 

Ans. — In former years simple engines were used alto- 



TYPES OF ENGINES — CLASSIFICATION 



185 



gether, but the later types are compound, either tandem 
or cross-compound. 

Ques. 479. — What styles of valves and valve-gears 
are in use on these engines? 

Ans. — Poppet-valves, actuated by long cam-driven! 
levers, are the most generally used. Other styles of 
valves, such as rotative valves, common slide and piston- 
valves, are also quite frequently used. 
Q 



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Fig. 122. 

The valve-gear of a Corliss engine with a single eccentric is shown in Fig. 122» 
The connections of the exhaust-valves with the wrist-plate are positive, and 
the travel of these valves is fixed, being a constant quantity, but the connection! 
of the steam-valves with the wrist-plate are detachable, being under the control 
of the governor. 



Ques. 480.- — What is meant in speaking of a fo« ^ 
valve engine? 

Ans. — An engine having two steam-valves and tvJ3 
exhaust-valves located near each end of the cylinder. 

Ques. 481. — What type of four-valve engine has met 
with great favor since its introduction? 

Ans. — The Corliss engine, invented by Mr. Geo. H# 
Corliss, of Providence, R. L 



186 



QUESTIONS AND ANSWERS 



Ques. 482. — What advantage does the four-valve 
engine possess over the single-valve type? 

Ans. — The advantage that each valve may be adjusted 
to a certain degree independently of the others, the steam- 
valves tor admission and cut-off and the exhaust-valves 
for compression and release. 

Ques. 483. — What is one of the oldest forms of valve, 
and one that is still used extensively, especially on 
marine engines? 

Ans. — The D slide-valve. 

L 




Fig. 123. 

Fig. 123 represents a slide-valve at mid-travel. S P— S P are the steam- 
ports and E P is the exhaust-port; the projections marked x at each foot <,£ 
the arch inside the valve represent inside lap, and may be added to or taken 
from the inside edges of the valve, according as more or less compression is 
desired- The dotted lines O L — O h represent outside lap. 

Ques. 484. — What are the functions of the slide- 
valve? 

Ans. — It controls the admission, expansion and release 
of the steam and the closure of the exhaust. 

Ques. 485. — Upon what does the development of the 
full power of the engine and its efficient and economical 
use of steam, as well as its regular and quiet action, 
largely depend? 

Ans. — Upon the correct adjustment of its valve or 
valves. 



TYPES OF ENGINES CLASSIFICATION 187 

Ques. 486. — How is the slide-valve fitted to the 
:ylinder? 

Ans. — The slide-valve has a flat face and it works on 
the corresponding flat face of the cylinder. In the 
cylinder face there are three passages called ports, the 
two smallest, called steam-ports, leading to each end of 
the cylinder, and the larger one, called the exhaust-port, 
eading to either the receiver, condensor, or the atmos- 
phere, as the case may be. The valve is contained in a 
team-tight chest or casing, either 'cast with the cylinder, 




Fig. 124. 

Fig. 124 shows the slide-valve in .the position of lead — exhaust opening has 
also occurred at the opposite end of the cylinder. The arrows show the course 
of the steam, also the direction in which the valve is traveling. 

or bolted to it. This casing or valve-chest is filled with 
live steam while the engine is working. 

Ques. 487. — How must the slide-valve be constructed, 
in order that it may properly perform the four important 
functions of admission, cut-oflf, release, and exhaust 
closure? 

Ans. — It must have lap and lead. 

Ques. 488.— What is lap? 

Ans. — Lap is the amount that the ends of the valve 
project over the edges of the ports when the valve is at 
mid-travel. 



188 QUESTIONS AND ANSWERS 

Ques. 489. — What is steam lap, or outside lap? 

Ans. — The amount that the end of the valve projects 
over the outside edge of the steam-port. 

Ques. 490. — What is inside or exhaust lap? 

Ans. — The lap of the inside or exhaust edge of th< 
valve over the inside edge of the port. 

Ques. 491.— What is lead? 

Ans. — The amount that the steam port is open when 
the piston is just commencing its stroke. This is the 
instant of admission. 

Ques. 492. — When is the instant of cut-off? 




/ Z 

Fig. 125. 
Fig. 125 shows the slide-valve at the end of its travel— full port opening. 

Ans. — When the admission of steam to the cylinder is 
stopped by the steam edge of the valve closing the steam- 
port and the piston is pushed the balance of the stroke by 
the expansion of the steam admitted before cut-off 
occurred. 

Ques. 493. — When is the instant of compression? 

Ans. — When the two inside or exhaust edges of the 
valve coincide with the inner edges of the ports, the piston 
being near the end of its stroke and the valve at mid- 
travel, 

Ques. 494. — When is the instant of release? 



TYPES OF ENGINES CLASSIFICATION 189 

Ans. — When the inner edge of the valve commences to 
;>pen the steam-port to the exhaust-passage. 

Ques. 495. — What is the advantage gained by com- 
ression? £ 

Ans.- — A portion of steam is confined ahead of the 

>iston, thus forming an elastic cushion to absorb the 

Inomentum of the piston and other moving parts con- 

mected with it and bring all to rest quietly at the end of 

the stroke. 

Ques. 496.— -How may this compression be increased | 
or diminished? 




Fig. 126. 

Fig. 126 illustrates the instant of cut-off. The valve is now traveling in the 
opposite direction. 

S • ' t " ' 

Ans. — By adding to or taking away from the inside 
lap of the valve. 

Ques. 497.— What is the object of giving a valve lead? 

Ans. — The effect of lead is to cause the engine to be 
quick and not to lag at the beginning of the stroke. The 
live steam admitted through the lead opening also assists 
in forming a cushion for the piston at the end of the 
stroke. 

Ques. 498. — Do the principles governing the adjust- 
ment and action of the slide-valve necessarily have to be 
applied in the adjustment and action of rotative, piston, 



190 



QUESTIONS AND ANSWERS 



and other forms of valves for controlling the distributio] 
of steam in the cylinders of engines? 

Ans. — They do. The same general principles applj 
in all cases. 

Ques. 499. — How is motion generally imparted to th| 
slide-valve or other types of valves? 

Ans. — By means of an eccentric, which is simply a cir| 
cular cast-iron or cast-steel sheave having a hole bored ii 
it eccentrically with its own circumference, and larg< 
enough to permit of its being fitted on the engine shaft 
The eccentric-sheave is either keyed on the shaft or helc 




Fig. 127. 
Fig. 127 shows the slide-valve at the instant of compression. 



in its place by set-screws, and therefore revolves with th< 
shaft. On the circumference of the eccentric, which is 
of sufficient width to present a good bearing surface, 
ring, called the eccentric-strap, works, and attached tc 
this ring is the eccentric-rod, which is either directly con- 
nected to the valve-rod, or valve-stem, or else impart! 
motion to the valve through the agency of a rocker-arm, 
and in many engines a link motion is used. The center 
of revolution of the eccentric being several inches apart 
from its center of formation, will, when the sheav< 
revolves with the shaft, cause the eccentric to convert th< 



TYPES OF ENGINES CLASSIFICATION 



191 



rotary motion into a reciprocating motion, which through 
the agency of the rod is imparted to the valve or valves. 

Ques. 500. — What is meant 
by the throw of an eccentric? 

Ans. — The distance be- 
tween the center of the eccen- 
tric-sheave and the center of 
the crank-shaft. This dis- 
tance is also called the radius 
of eccentricity. 

Ques. 501. — What is meant 
by eccentric position? 

Ans. — The location of the 
highest point of the eccentric 
relative to the center of the 
crank-pin, expressed in de- 
grees. 

Ques. 502. — What is ang- 
ular advance? 

Ans. — The distance that 
the high point of the eccentric 
is set ahead of a line at right 
angles with the crank, in other 
words, the lap angle plus the 
lead angle. 

Ques. 503. — If a valve had 
neither lap nor lead, what 




Fig. 128. 



Fig. 128 shows an eccentric with 
its strap and rod. E is the sheave, 
the center of which is shown at D. 
A is the center of the shaft. The WOUld be the position of the 
distance A D represents the throw of 

the eccentric and twice that distance hicrh nninf rvf tVi£» t*rr(*n+rii* 
equals the travel of the end B of the fll & n P umi UI tne CCCCIUTC 
rod along the line A F. S is the ec- 
centric strap 



relative to the crank? 



192 



QUESTIONS AND ANSWERS 



motion, using tw<? 



Ans. — It wottld be on a line exactly at right angles 
with the crank, as, for instance, the crank being at 
degrees, the eccentric would stand at 90 degrees. 

Ques. 504. — How is the reversing of modern marine 
engines usually effected? 

Ans. — By means of the link 
eccentrics. 

Ques. 505. — How many varieties 
of links are in" use? 

Ans. — Three, the slotted link, 

the solid-bar link and A the double- 

* 

bar linlj. 

Qu£s. 506.— Describe the slotted 
link. 

Ans. — It is a curved bar with a 
slot cut in it, in which tlie link-block 
is fitted. This link-block is attached 
to the valve-rod by a pin, about 
which an oscillating motion oi the 
block occurs. Two projections are 
forjned on one side of the link, to 
which the eccentric rods are connected. 

Ques. 507. — Describe the solid-bar link. 

Ans — The solid-bar link consists of a simple, curved, 
rectangular bar, with eyes formed at each end, for con- 
necting the eccentric-rods. The solid bar passes through 
the block. 

Ques. 508. — What is the general plan of the double- 
bar link? 

Ans. — It consists of a oair of curved steel bars joined 




Fig. 129. Slotted Link. 



TYPES OF ENGINES CLASSIFICATION 



193 



at the ends and kept a certain distance apart by distance 
pieces. Projecting pins are formed on the link-bars, two 
on each side, for the attachment of the eccentric-rods. 
The ends of the eccentric-rods are forked and contain each 
two adjustable bearings, which embrace the pins on each 
side of the link. The link-block is a steel or iron pin, 
sliding between the bars, and having projections on each 




Fig. 130. Soud Bar I^ink. 

side which embrace the link-bars and through which thefc 
bars slide, on adjustable gun-metal liners. 

Ques. 509. — Why is it necessary that the link shouV 
be curved? 

Ans. — For the reason that it is used not only for 
reversing the engine, but also for working steam expan- 
sively, and therefore its shape must be such that when the 
block is in any intermediate position the center of the 
travel of the valve will always be constant, otherwise the 



194 



QUESTIONS AND ANSWERS 



distribution of the steam to the two ends of the cylinder 
frould not be evenly divided. 

Ques. 510.— What is the slip of the linic? 

Ans. — A slight oscillating movement of the link on its 

block. 

Ques. 511.— What is it that fixes the curvature of the 
link? 

Ans. — The length of the eccentric-rod; that is, the 
curve of the link is a circular arc, of a radius equal to the 



=7 



Qji^ c; |ioT 



© 



a 




n 



Fig. 131. Plan View of Double- Barjed Link. 

distance between the center of the eccentric and center of 
the pin at the end of the rod. 

Ques. 512. — Is there a type of reversing valve-gear 
that employs but one eccentric? 

Ans. — There is, viz., the Marshall radial valve-gear. 

Ques. 513. — It there a type of reversing valve-gear iq| 
which eccentrics are dispensed with? 

Ans. — There is, viz., the Joy valve-gear, by which the| 
motion of the valve is derived from the connecting rod, 
through the medium of a vibrating link, one end of which I 



TYPES OF ENGINES — CLASSIFICATION 



195 



is jointed to the connecting rod while the other end is 
constrained to move in a horizontal or vertical direction 
by the action of a radius rod. This motion is horizontal 
if the engine is a vertical engine, or vertical if the engine 
is horizontal. One end of another rod works on a pin in 
the vibrating link and near the other end of this rod is a 
fulcrum carried by a pin attached to sliding blocks on 
each side, working in sectors, which are carried by the 
reversing shaft. Motion is communicated to the valve 





Fig. 132. 



Fig. 132 shows details of the construction of the link-block for a double* 
barred link. 

from a point in the last-mentioned rodb2yond the fulcrum 
carried by the sectors attached to the reversing shaft. 

Ques. 514. — How is the forward or backward move- 
ment of the engine effected with the Joy valve-gear? 

Ans. — By inclining the sector on one or the other side 
of the center line of the reversing shaft and the point of 
cut-off and consequently the amount of expansion depends 
upon the amount of the inclination, the central position 
being mid-gear. The reversing arm moves these sectors 



196 



QUESTIONS AND ANSWERS 



to the required position. In large marine engines th( 
reversing mechanism is operated by a small starting 
engine. On locomotives and small engines it is operated 
by hand. 

Ques. 515. — Mention one of the advantages possessed 
by the Joy valve-gear, over the double eccentric and link 
motion. 

Ans. — By this gear a constant lead is secured for all 
Unked-up positions. 




Fig. 133. Stevenson Link Motion for Marine Engine. 

On the crank-shaft C there are keyed two eccentrics, one in the position to 
give ahead motion and the other in the position for astern motion. The eccentric 
rods are of equal length, and their ends are attached by working joints to the 
opposite ends of a curved link, L,. 

Ques. 51G. — Is the Joy valve-gear much in use? 

Ans. — It is applied to a large number of marine 
engines and locomotives. 

Ques. 517. — How is the lifting valve-gear of the 
marine beam engine actuated? 

Ans. — By curved cams keyed to a transverse shaft 
Fsur cams are fitted, two for steam and two for exhaust 



^ 



TYPES OF ENGINES — CLASSIFICATION 



197 



Ques. 518. — How is the oscillating movement imparted 
to the transverse shaft? 

Ans. — From rocker-arms, one on each end of the 




Fig. 134. 

The Marshall Valve-gear. The single eccentric, turning witi: the crank, 
orks the valve through a pivoted arm. The movement of the engine may be 
opped or reversed by sliding the hand-lever on the notched quadrant. The 
op paths show the movement of the valve rod-pin and also of the valve an 
srtical directions for ahead or backing motion. 



r 



198 



QUESTIONS AND ANSWERS 




Fig. 135. 

Fig. 135 shows an elevation and plan of the latest arrangement of Joy's valve- 
gear applied to a vertical engine. In this gear eccentrics are dispensed with, and 
the movements of the slide-valve obtained from the connecting rod. The vibra- 
ting link B. jointed to the connecting rod at A, has one end constrained to move 
horizontally by the action of the radius rod C. One end of another rod, D, 
works on a pin in the vibrating link B; near the other end is a fulcrum carried 
by a pin F. attached to sliding blocks on each side working in sector G, which 
are carried by the reversing shaft, the center line of the sector passing through 
the center of the reversing shaft. From D the motion is communicated to the 



TYPES OF ENGINES — CLASSTFI CATION 19tf 

slide-valve rod by means of the link E, attached to a point K in the rod D beyond 
the fulcrum F. 

The forward or backward movement of the engine is governed by inclining 
the sector on one or the other side of the horizontal center line, and the amounft 
of expansion depends on the amount of the inclination, the exactly central or 
horizontal position being 'mid-gear.' The reversing arm F R moves these sectors 
to the required position, and its extremity R is connected to the starting engine 
H. The paths of the point A in the connecting rod, and also of the point B in 
the vibrating link, as the engine revolves, are indicated by dotted lines, as are 
also the extreme positions of the sector center lines for ahead and astern working 
' respectively. The gear as drawn is in the stop position. By this gear a constant 
lead is secured for all linked-up positions, since when the piston is at the top or 
bottom of the stroke the pin F co-incides with the center of the reversing shaft, so 
that in this position any movement of the sectors does not affect the position of 
the slide-valve. The up and down motion of the point B therefore gives a 
constant movement of the valve equal to the lap plus the lead, while the 
horizontal motion sliding the block to and fro in the sectors adds the amount 
required for steam opening, this amount increasing with the angle of the sector 
to the horizontal. 

transverse shaft, the pins of which are engaged by hooks 
in the eccentric-rods. 

Ques. 519. — How are the poppet-valves of the West- 
ern river boat actuated? 

Ans. — By cams very similar to those on the beam 
engine. 

Ques. 520. — Describe the construction and action of 
a double-ported slide-valve. 

Ans. — A double-ported slide-valve acts in a manner 
similar to a single-ported valve in the admission of steam, 
but in addition there is what is practically an inner valve, 
to which steam is admitted through passages formed in 
the body of the valve* There are also two inner ;\)rts in 
addition to the two ports at the ends of the cylinder, ^nd 
these inner ports or passages also lead to and are in con - 
nection with the end ports. 

Ques. 521. — What is the object in using a double- 
ported valve? 

Ans. — To reduce the travel of the valve, which in 
large engines would be too great with a single-ported 
valve. 



200 



QUESTIONS AND ANSWERS 



Ques. 522. — Are treble-ported valves used to any 
large ext mt? 

Ans. — They are, on large marine engines, their action 
being on the same general principles as the double-ported 
slide-valve. 




Fig. 136. Joy's Assistant Cylinder 

This consists of a small cylinder and steam-piston attached to the valve* 
aplndle. The cylinder has a central inlet for steam, A, and two exhaust-portSi 
B, one for each end, leading to a common exhaust-pipe, and the piston is so 
constructed that by its motion the operations of steam admission, cut-off, release 
and compression are performed on each side of the piston. The apparatus i: : 
therefore, a small engine which exercises a force on the valve to move it up of 
down, and cushions steam at each end to absorb the momentum forces. These 
assistant cylinders give diagrams similar to that of an ordinary engine; they 
exert from 15 to 25 I. H. P. each for the sizes fitted in marine engines, and the 
amount of power developed can be adjusted by means of a valve on the steam- 
pipe. If the main valve be linked in. the assistant cylinder is also automatically 
similarly affected. 



TYPES OF ENGINES CLASSIFICATION 



201 



Ques. 523. — How is the pressure of the steam on the 
back of a large, flat slide-valve lessened and relieved? 
Ans. — By relief packing rings. 

Ques. 524. — How are 
relief packing rings fitted? 
Ans. — They are some- 
times fitted on the back of 
the valve, but are generally 
fitted on the valve-chest 
cover, and are pressed out 
by springs so as to work 
steam-tight on a planed 
surface, either on the back 
of the valve or, on the in- 
side of the cover, thus re- 
ducing the area on which 
the steam-pressure can act. 
The space inside the pack- 
ing ring is connected to the 
condensor or the receiver of 
the succeeding engine. 

Ques. 525. — Do relief 
rings work in a satisfac- 
tory manner? 

Ans. — They do not, as 
a general thing, being 
troublesome to make effi- 
cient, and they also are difficult of adjustment. 

Ques. 526. — What form of slide-valve has been found 
to give good satisfaction, especially on the high and inter- 
mediate cylinders of la r &e marine engines? 




Fig. 137. Double-Ported Valve. 



202 QUESTIONS AND ANSWERS 

Ans. — The piston slide-valve, consisting of two 
pistons connected together and working steam-tight in 
cylindrical chambers that contain the steam-ports. The 
face of each of the pistons corresponds to the face of the 
single-ported slide-valve, and performs the same functions, 

Ques 527. — What means are provided in large verti- 
cal engines for preventing the weight of the slide-valve, 
rod, and link gear from bearing upon the eccentric? 

Ans. — Balancing pistons, working in small steam- 
cylinders in the top end of the valve-casing. 

Ques, 528. — What is meant by setting the valve, or 
valves of an engine? 

Ans. — The adjustment and securing of the slide-valve 
in its proper position on the rod so as to secure the 
correct distribution of the steam in the cylinder. This 
also includes the fixing of the eccentric in its correct 
position on the shaft. 

Ques. 529, — What is the first, or one of the first, 
moves in valve-setting? 

Ans. — The rods and gear are first coupled together, 
and the crank is placed on the dead center. 

Ques. 530. — What is the meaning of the expression 
dead center? 

Ans. — An engine is on the dead center when the crank 
is in line with the piston-rod, that is, when the centers of 
the crank-shaft, crank-pin. and cross-head pin are exactly 
in line, so that the pressure of the steam on the piston 
exerts no turning moment on the shaft, but produces only 
direct thrust, subjecting the shaft to bending action only. 

Ques. 531. — With the engine on the dead center and 



TYPES OF ENGINES — CLASSIFICATION 203 

the rods and valve-gear all coupled up 3 what is the next 
move in valve-setting? 

Ans. — The slide-valve, by means of screws and nuts 
on the valve-rod, is fixed in the proper position to give 
the required lead for the corresponding end of the cylinder. 
The shaft is then turned around until the crank is on the 
opposite dead point and the lead of the valve for that 
end of the cylinder is measured. If the amounts of lead 
at the opposite ends are different, the position of the slide- 
valve on the rod should be adjusted by means of the nuts 
and screws, until the leads are either equal, or differ by 
the desired amount. The valve should then be perma- 
nently secured on the rod, so that its position may not 
alter. This is called equalizing the lead. 

Ques. 532. — If, after having gotten the lead equalized, 
it is found that there is too much or too little, how may 
it be decreased, or increased without altering the position 
of the valve on the rod? 

Ans. — To decrease the lead, reduce the angular 
advance of the eccentric, and to increase the lead it is 
necessary to increase the angular advance. 

Ques. 533. — What is the rule generally observed 
Regarding the lead on large vertical engines? 

Ans. — In vertical engines, owing to the weight of the 
loving parts, the lead on the lower end is generally 
lade slightly greater than the lead on the upper end, and 
tore exhaust lap is allowed. In such cases the valve is 
;et on the rod to give the required difference between the 
:wo leads. Then, if the lead be too great or too small at 
>oth ends, the required change may be made by moving 
ie eccentric ahead or b*cV -in tf\e *Vaf*- 



204 



QUESTIONS AND ANSWERS 



Ques. 534. — Is the position of the eccentric on the 
'ihaft necessarily fixed on all types of engines? 

Ans. — It is not. Many high-class stationary engines 




Fig. 138. Piston Valve, 



arc 6tted \tith isochronol or inertia governors, whi 
control the position of the eccentric and vary the poin 



t 
cfc I 



TYPES OF ENGINES CLASSIFICATION 205 

of cut-off according as the load on the engine is light or 
heavy, thus maintaining a regular speed. 

Ques. 535. — What types of valves are used with 
isochronol governors? 

Ans. — Slide-valves of various patterns; box-valves, 
in which the steam passes through the valve; piston 
valves, in which the steam either passes through or 
around the ends of the valve. 

Ques. 536. — In all types of reciprocating engines the 
same factors affecting the distribution of the steam are 
)resent. What are they? 

Ans. — Outside lap, affecting admission and cut-off, 
md inside lap, affecting release and compression. 

Ques. 537. — How are these factors distributed in the 
our-valve type of engine? 

Ans. — They are distributed among the four valves, 
ach valve performing its own particular function in the 
istribution of the steam for the end of the cylinder to 
rhich it is attached. 

Ques. 538. — What advantage is there connected with 
etting the valves of a four-valve engine, as compared 
rith a single valve? 

Ans. — Each valve may be adjusted to a certain degree 
ldependently of the others, thus, for instance, the steam- 
alves of a Corliss engine may be adjusted to cut off the 
:eam at any point from the beginning up to one-half the 
:roke, without in the least affecting the release or com- 
ression, because these latter events are controlled by the 
thaust- valves. 

Ques. 539.— What is the first requisite in setting the 
Ives of a Corliss 



206 



QUESTIONS AND ANSWERS 



Ans. — To place the crank on the dead center. 

Ques. 540. — What is the next move? 

Ans. — To adjust the length of the hook-rod, if it is 
adjustable; if not, then the length of the eccentric-rod, 
so that the wrist-plate will vibrate equal distances each 




C WKtst ptafe ) 



^i r 


-r. 



w 



Fig. 139. Wrist Plate op Corliss Engine. 



way from its central position, which is marked on top of 
the hub. 

Ques. 541. — How should the rocker-arm, that carries 
the eccentric-rod, and hook-rod be adjusted? 

Ans. — The length of the eccentric-rod should be such 



TYPES OF ENGINES CLASSIFICATION 



207 



that the rocker-arm will vibrate equal distances each way 
from a vertical position. 

Ques. 542. — How may the vibration of the wrist-plate 
and rocker-arm be tested? 

Ans. — By connecting the eccentric-rod and the hook- 
rod in their proper places, and turning the loose eccentric 
around on the shaft in the direction the engine is to run. 

Ques. 543. — Having gotten these important adjust- 
ments correctly made, what is the next step in setting 
Corliss valves? 

Ans. — Remove the back bonnets from the four valve 




Fig. 140. Steam- Vaeve of Corliss Engine. 



chests, and while neither the working edges of the valves 
nor the ports can be seen, yet certain marks will be found 
on the ends of the valves and corresponding marks on the 
faces of the chests, which serve as a guide in setting the 
valves. 

Ques. 544. — Having removed the bonnets and found 
the marks, what is to be done next? 

Ans. — Temporarily secure the wrist-plate in its 
central position by tightening one of the set-screws on 
*He eccentric. Then connect the valve-rods to the wrist- 



208 



^QUESTIONS AND ANSWERS 



plate and to the small crank-arms attached to the ends of 
the valves, adjusting their lengths so that the steam- 
valves will have from Y\ to t 9 6 inch lap, and the exhaust 
valves from ^V to tV inch opening. 

Ques. 545. — In adjusting the steam-valves, what par* 
ticular detail should be carefully noted? 

Ans. — The direction in which the valves turn to open 
should be noted. In most Corliss engines the arm of the 
small crank to which the valve-rod is connected, extends 




Fig. 141. Exhaust- Vai«vE otf Coruss Engine. 



downwards from the valve-stem. This will cause the 
valve to move towards the wrist-plate in opening. 

Ques. 546. — After the valve-rods have been properly 
adjusted as to length, what is the next move? 

Ans. — Place the engine on the dead center — either 
center will do — and move the eccentric around on the 
shaft in the direction the engine is to run, until the 
eccentric is far enough ahead of the crark to allow the 
steam-valve for that end of the cylinder the proper 
amount of lead opening, which will vary according to the 
size of the engine. Then tighten the eccentric set screws 



TYPES OP ENGINES — CLASSIFICATION 



209 



and tr.rn the engine around to the opposite center and 
note whether the lead is the same on both ends. 

Ques. 547. — In case there is a difference in the lead 
for the two ends, how may it generally be equalized? 

Ans. — By slightly altering the length of one of the 
valve-rods. 

Ques. 548. — What is the next point to receive atten- 
tion, in setting Corliss valves? 

TABLE 8 

LAP AND LEAD OF CORLISS VALVES 



Size of Engine. 


Lap of Steam 


Lead Opening of 


Lead Opening of 


Valve. 


Steam Valve. 


Exhaust Valve. 


12 inches 


J inch 


^s inch 


i % inch 


14 " 


A " 


A " 


A " 


16 " 


t 5 t " 


* 


A " 


18 


1 " 


1 <« 
1* ,. 


A " 


20 " 


8 


a 


A " 


22 " 

24 


k" 


A 


A ' 

a * 


26 


A " 


a : 


A " 


28 


h " 


A 


ft •; 


30 •• 


k " 


A " 


* : 


32 


i " 


a :: 


i ** 


34 4< 


h " 


1 « 

8 


1 ** 


36 ■' 


\ " 


* ' 


* « 


38 ■• 


1% " 


*■ 


A 


40 


A " 


^ 


A 


42 


ft " 


8 " 


A " 



Ans. — The adjustment of the lengths of the rods 
extending from the governor to the releasing mechanism^ 
so that the valves will cut off at equal points in the 
stroke. 

Ques. 549. — How is this adjustment accomplished? 

Ans. — By raising the hook-rod clear of the wrist-plate 
pin and with the bar provided for the purpose, move the 



•210 QUESTIONS AND ANSWERS 

wrist-plate to either one of its extreme positions, as 
shown by the marks on the hub, and, holding it in this 
position, adjust the length of the governor-rod for that 
steam-valve (which will then be wide open) so that the 
boss or roller which trips the releasing mechanism is just 
in contact, or within ?V inch of it. Then move the wrist- 
plate to the other extreme of its travel and adjust the 
length of the other rod in the same manner. 

Ques. 550. — How may the accuracy of this adjust- 
ment be tested? 

Ans. — Raise the governor-balls to their medium 
position, or about where they would be when the engine 
is running at its normal speed, and block them there. 
Then having again connected the hook-rod to the wrist- 
plate, turn the engine around in the direction in which it 
is to run, and when the valve is released by the trip, 
measure the distance upon the guide that the cross-head 
has traveled from the end of the stroke. Now continue 
to turn the engine in the same direction until the other 
valve is released, and measure the distance that the cross- 
head has traveled from the opposite end of the stroke, 
and if these two distances are the same, the cut-off is 
equalized. If there is a difference, lengthen one rod and 
shorten the other until the point of cut-off is the same for 
both ends. The lengths of the dash-pot rods should also 
be adjusted, so that when the plunger is at the bottom of 
the dash-pot the valve-lever will engage the hook* The 
io*k-nuts on all rods should then be securely tightened. 



(4 
*« 
M 

«< 



CHAPTER VII 

CONDENSERS — AIR-PUMPS — SEA- WATER 

Ques. 551. — What is the average composition of sea- 
water? 

Ans. — Sea-water contains about 3*2 part of its weight 
of solid matter, of which common salt (sodic chloride) is 
the principle constituent. The average composition of 
the solid matter in sea-water may be taken as follows: 

Sodic chloride, or common salt 76 per cent 

Magnesic chloride .10 

Calcic sulphate, or gypsum 5 

Magnesic sulphate 6 

Carbonate of lime, and organic*matter 3 

Ques. 552. — Does the common salt in sea-water cause 
much trouble for the marine engineer? 

Ans. — It does not, for the reason that it remains 
soluble in water at all temperatures, and there is no 
deposit of salt, except under extreme circumstances. 

Ques. 553. — What is the principal scale-forming 
ingredient in sea-water? 

Ans. — Sulphate of lime, or calcic sulphate. Deposit 
is also formed by sulphate of magnesia, although it is less 
objectionable than the lime deposit. 

Ques. 554. — At what temperature does the sulphate 
of lime become insoluble in water and form a deposit on 
the boiler plates? 

Ans. — At a temperature of 280 degrees to 295 degrees 

311 



212 QUESTIONS AND ANSWERS 

Fahrenheit, corresponding to a pressure of 35 to 
45 pounds pressure of steam by the gauge. As the tem- 
perature of the water rises, the other sulphates become 
insoluble, and at 350 degrees Fahrenheit, or 120 pounds 
gauge-pressure, sea-water is incapable of holding any 
sulphates in solution. 

Ques. 555. — What other cause, besides a high tempera- 
ture, tends to precipitate these salts? 

Ans. — Increase of density, caused by evaporation of 
the water, even if the temperature remains about 
212 degrees Fahrenheit. Sulphate of calcium is thus 
deposited at a density of sV Common salt does not 
crystallize out until a density of about A is reached. 

Ques. 556. — When was it possible to use sea-water 
for feeding boilers? 

Ans. — In the early days of marine engineering, when 
a low-pressure (35 to 45 pounds) was carried, and the 
jet condenser was used, in which the steam was exhausted 
into the condensing chamber, where it came into actual 
contact with and was condensed by a jet of cold sea- 
water. The feed-water for the boilers was drawn from 
this mixture of sea-water and condensed steam, conse- 
quently a large quantity of sea-water was sent into the 
boilers, but as the temperature was low and the density 
was not allowed to exceed ?*, the salts were held in 
solution fairly well. 

Ques. 557. — How was the increase of density pre- 
vented? 

Ans. — By blowing off a portion of the denser boiler- 
water at stated times, and making up the loss by ad- 



CONDENSERS — AIR-PU M PS — SEA-WATER 213 

mitting a larger quantity of salt water. This was termed 

"brining the boiler.' ' 

Ques. 558. — What led to the introduction of the 
surface condenser? 

Ans. — With the advent of high pressures, it was 
found impossible to prevent the deposit of scale, and all 
of its attendant evils. It was therefore found necessary 
to condense the exhaust steam without bringing it into 
actual contact with the condensing water, hence the sur- 
face condenser was designed. 

Ques. 559. — Mention two of the principal advantages 
gained by the use of the surface condenser. 

Ans. — First, by its use fresh feed-water is obtained 
for the boilers; second, the condition of the condensing 
water is of no importance, as regards the feed-water so 
that, no matter whether it is salt, muddy, acid, or other- 
wise impure, pure water is always obtained for the 
boilers, provided the condenser is maintained in good 
condition and no leakage is allowed to occur. 

Ques. 560. — What is the meaning of the word 
vacuum? 

Ans. — That condition existing within a closed vessel 
during the absence of all pressure, including atmospheric 
pressure. 

Ques. 561. — How is a vacuum measured? 

Ans. — It is measured in inches of a column of mer- 
cury contained within a glass tube a little more than 
30 inches in height, having its lower end open and immersed 
in a small open vessel filled with mercury. The upper 
end of the glass tube is connected with the vessel in which 



214 QUESTIONS AND ANSWERS 

the vacuum is to be produced. When no vacuum exists, 
the mercury will leave the tube and fill the lower vessel. 
When a vacuum is maintained within the condenser, or 
other vessel, the mercury will rise in the glass tube to a 
height corresponding to the degree of vacuum. If the 
mercury rises to a height of 30 inches it indicates a per- 
fect vacuum, which means the absence of all pressure 
within the vessel, but this condition is never realized 
in practice, the nearest approach to it being about 
28 inches. 

Ques. 562. — Is the mercurial vacuum-gauge used in 
every-day practice? 

Ans. — For purposes of convenience it is not generally 
used, it having been replaced by the Bourdon Spring- 
gauge, although the mercury-gauge is used for testing. 

Ques. 563. — What is the advantage, from a purely 
economic standpoint, in allowing the exhaust steam to 
pass into a condenser in which a vacuum is maintained 
rather than to allow it to exhaust into the open air? 

Ans. — In a non-condensing engine, that is, an engine 
in which the exhaust steam passes into the open air, the 
pressure of the atmosphere, amounting to 14.7 pounds 
per square inch at sea-level, is constantly in resistance to 
the motion of the piston. Therefore the exhaust or ter- 
minal pressure can not fall below the atmospheric pres- 
sure and is generally from 2 to 5 pounds above it, caused 
by the resistance of bends, and turns in the exhaust pipe, 
or other causes which tend to retard the free passage of the 
steam. On the other hand, if the steam were allowed to 
exhaust into a condenser in which a vacuum of 25 inches 



CONDENSERS AIR-PUMPS SEA- WATER 



215 



is being maintained, the terminal pressure or back pres- 
sure in resistance to the forward motion of the piston 
would be but 2.5 pounds, and if a vacuum of 28 inches 
existed in the condenser there would be practically no 
back pressure, thus making available for useful work the 
14.7 pounds of steam which in the non-condensing engine 
was required to overcome the resistance of the atmos- 
pheric pressure. 

Ques. 564. — Is it proper, then, 
to consider the vacuum in a con- 
denser as power? 

Ans. — The vacuum can not be 
considered as power at all. It oc- 
cupies the anomalous position of 
increasing, by its presence, the ca- 
pacity of the engine for doing work. 

Ques. 565. — How is the vacuum 
in a condenser usually maintained? 

Ans. — By a pump called an air- 
pump, although a partial vacuum 
can be produced by the mere conden- 
sation of the exhaust steam as it enters the condenser, by 
allowing a spray of cold water to strike it. The steam when 
it first enters the condenser drives out the air and the vessel 
is filled with steam at a low pressure, which 3 when con- 
densed, occupies about 1,600 times less space than it did be- 
fore being condensed, hence a partial vacuum is produced. 
The action of the siphon injector is based upon this principle. 

Ques. 566. — Describe the construction and action of 
the siphon condenser. 




Fig. 142. 
Siphon Condenser. 



*16 



QUESTIONS AND ANSWERS 



Ans. — The siphon condenser is a form of jet condenser 
in which no air-pump is used. In this t3 r pe of condenser 
the supply of condensing water is drawn from outside 
pressure, either from an overhead tank, or other source, 



iXHAUST 

tNter 




Fig. 143. Knowles Jet Condenser. 



and passing into an annular enlargement of the exhaust- 
pipe, is discharged downwards in the form of a cylindrical 
sheet of water, into a nozzle which gradually contracts. 
The exhaust steam, entering at the same time, is con- 



CONDENSERS AIR-PUMPS SEA-WATER 



21? 



densed and the contracting neck of the cone-shaped nozzle 
gradually brings the water to a solid jet and it rushes 
through the nozzle with a velocity sufficient to create a 
vacuum. This type of condenser can only be used where 
the discharge pipe has a perfectly free outlet. 

Ques. 567. — Describe in general terms the construc- 
tion and action of the jet condenser. 

Ans. — The jet condenser is usually a vertical, cylindri- 



ifi * "">" 




/hr&u7i£> 



Fig. 144. Sectionae View of a Surface Condenser and Independent Air 

and Circulating Pumps'. 



cal, cast-iron vessel, made air-tight, and which receives 
the exhaust steam from the low-pressure cylinder. In 
modern plants, condenser-shells are often made of sheet 
steel in cylindrical shape, reenf orced with stiffening rings. 
The exhaust steam enters at the top and the condensing 
water enters usually at the side, flowing in through the 
spraying nozzle, and, discharging through a large num- 
ber of small holes, comes in contact with the steam in the 



218 QUESTIONS AND ANSWERS 

form of spray, thus producing a quick condensation while 
falling to the bottom of the condenser, to be drawn off by 
the air-pump. A cock or valve is fitted in the injection 
pipe, for the purpose of regulating the supply of cooling 
water. 

Ques. 568. — Why is an air-pump a necessary part of a 
^reliable jet-condensing apparatus? 

Ans. — The mixture of condensing water and con- 
densed steam must be pumped away constantly, also the 
condensing water always contains a certain volume of 
air in solution, which may be liberated, either by boiling 
it or by reducing the pressure to which it is subjected. 
This air is liberated in the condenser, and if it is not 
pumped away regularly, it is liable to accumulate and 
spoil the vacuum. 

Ques. 569. — How may the dimensions of a single-act- 
ing air-pump for a given sized engine be determined? 

Ans. — In the solution of this problem, two factors 
must be considered: First, the total volume of the low- 
pressure cylinder; second, the density of the exhaust 
steam. The volume of the air-pump cylinder is then 
found by the following rule: Multiply the volume of the 
low-pressure cylinder in cubic feet by 3.5, and divide the 
product by the number of cubic feet contained in 1 pound 
weight of exhaust steam at the pressure at which it 
enters the condenser. This rule applies only to jet con- 
densers. 

Ques. 570. — Describe the construction and action of 
the surface condenser. 

tins. — The surface condenser, like the jet condenser. 



CONDENSERS — AIR-PUMPS — SEA- WATER 



219 



is an air-tight iron or steel vessel, either cylindrical or 
rectangular in shape, but, unlike the jet condenser, it is 
fitted with a large number of brass or copper tubes of 
small diameter (generally about Yz inches), through which 
cold water is forced by a pump called a circulating 




Fig. 145. 



Side view of large cylindrical horizontal surface-condenser having two 
exhaust-inlets. The tubes are not shown. The steam enters at the orifices marked 
A, and is withdrawn, when condensed, through the orifice B by the air-pump. 
The circulating water enters at C, and is confined by the diaphragm D to the 
lower half of the tubes, and, having traversed these tubes, it returns through the 
upper half of the tubes, being finally discharged to the sea through the pipe E. I 
T. T. are the tube-plates near the ends of the condenser casing. 

pump. A vacuum is maintained in the body of the con- 
denser by the air-pump, and the steam exhausting into 
this vacuum is condensed by coming in contact with the 
cool surface of the tubes. Or, as is often the case, the 
exhaust steam passes through the tubes instead of around 



220 



QUESTIONS AND ANSWERS 



them, and the cooling water is forced into and through 
the body of the condenser, the vacuum in this case being 
maintained in the tubes. The tubes may be placed either 
vertical or horizontal. When the steam is passed through 
the tubes, they are generally placed vertical, while, on the 



Ct*cut*rm6 **r& 
ouutf 







Fig. 146. End Sectional View op Cylindrical Horizontal Surface 
Condenser, Showing a Portion op the Tubes. 

other hand, if the water circulates through them they are 
placed horizontal. The system of causing the water to 
circulate through the tubes, the steam surrounding them, 
is the more general. 



CONDENSERS AIR-PUMPS SEA- WATER 



221 



Ques. 571. — How are the tubes generally arranged in 
a surface condenser? 

Ans. — They are arranged in one or more systems, so 
that the condensing water passes through the condenser, 
usually twice, the coldest water entering at the bottom 
and coming in contact with the steam at its lowest tem- 
perature, and the warmest water at the top meeting the 

hottest steam. The exhaust 
steam enters at the top and 
after passing over the cold 
tubes is removed in the form 
of water, by the air-pump. 
The steam is directed in its 
downward course by baffle- 
plates, thus securing complete 
utilization of the cooling sur- 
face. A space is provided at 
the bottom of the condenser 
for the accumulation of the 
water of condensation below 
the cooling surface. The con- 
denser casing or shell for naval 
vessels is either cast in brass or else built up from com- 
position sheets, in order to save weight and prevent cor- 
rosion and galvanic action, which would be more liable 
to take place with an iron or steel shell. 

Ques. 572. — How are the tules secured in their places? 

Ans. — Brass or composition tube-plates are placed in 

the shell, near each end, sufficient space being' left 

between the outside cover-plates and the tube-plates iv» 




Fig. 147. Detail of Wick and 
Gland Packing for the Tubes 
of a Surface Condenser. 



222 



QUESTIONS AND ANSWERS 



the circulation of the cooling water. Into these plates, 
which are thick enough to furnish a good bearing for the 
tubes, the ends of the tubes are fitted and packed thor 
oughly tight, sometimes with a wood packing, sometimes 
with small screwed stuffing boxes with glands and fol« 
lowers, which tighten upon wick packing. The wood 
packing consists of a small soft wooden sleeve, which is 
forced into the small hole over the tube end in a dry 
state, and after becoming wet it swells and clamps the 




Fig. 148. Method op Packing Tubes of a Worthington Surface Condense*. 

One end of each tube is flanged and rigidly held in the tube head by means 
of a screw follower; the other end of the tube passes through an adjustable 
gland, which permits of free movement of the tube during expansion and 
contraction. This method of securing rigidly one end of the tube reduces the 
number of glands or stuffing-boxes to just one-half the number found in ordin- 
ary condensers. The glands can be readily removed and the packing replaced 
if it becomes leaky from long use. 

I 

tube, thus forming and preserving a tight joint so long 
as it is kept wet. 

Ques. 573. — Which kind of packing is the most reli- 
able for condenser tubes? 

Ans. — The gland and wick, for the reason that it 
always remains tight, while on the other hand the wood 
packing will shrink and become loose if the condenser is 
out of service for a time. , 



CONDENSERS AIR-PUMPS — SEA-WATER 223 

Ques. 574. — What are the usual dimension* of the 
tubes of surface condensers? 

Ans. — They are generally about % inches in diameter, 
are made of brass, about ?V of an inch thick, of a com- 
position consisting of not less than 70 per cent of coppei 
and not less than 1 per cent of tin, the remainder being 
zinc, the small quantity of tin being added to prevent 
galvanic action. The tubes are pitched not less than |J 




Fig. 149. Worthington Surface Condenser, with Air and Circulating 

Pump. 

inches apart in order to allow sufficient material for the 
gland. They are zigzagged so as to occupy as small a 
volume as possible. Condenser tubes vary considerably 
in length, depending upon the size of the condenser, the 
usuai length in large condensers being from 8 to 10 feet,, 
while in some very large condensers the tubes are 14 or 
15 feet in length. The tube-plates are about 1 inch thick, 
in order to provide sufficient depth for the gland and 
packing for the tubes. 



*£4 



QUESTIONS AND ANSWERS 



Ques. 575. — What type of air-pump is generally used? 
Ans. — The vertical single-acting air-pump has been 



cover removed. 



Throuoh muft 
cyhncter. 




ptwrmmg.^wB^i^wA 



Fic. 150. 

Section cf Blake independent air-pump, fitted in many vessels, including 
several U. S. warships. There are two steam-cylinders and two single acting 
vertical air-pumps of the usual type. It works at slow speed and give* excel* 
tent results. 



^ 



CONDENSERS AIR-PUMPS SEA-WATER 225 

found to be the most efficient. In vertical engines the air- 
pump generally receives its motion from the cross- 
head of the engine, through the medium of a short 
walking-beam. There are, however, a great many 
engines fitted up with an independent air-pump and 
condenser, in which the air-pump is simply an ordinary 
double-acting steam-pump, having its own steam- 
cylinder, and may be operated independently of the engine, 
which is a great advantage, as there is not so much 
danger of the water from the condenser backing up into 
the cylinder in case of a sudden shut-down of the engine, 
which is liable to occur with a jet condenser. 

Ques. 576. — Describe the parts of the vertical single- 
acting air-pump. 

Ans. — It consists of the barrel, or cylinder, the suc- 
tion-channel way at the bottom, the cover, with delivery- 
channel way and the hot well, the whole being made air- 
tight. The moving parts are the bucket, or piston, with 
its valves, the foot-valves and the head-valves. 

Ques. 577. — Describe the arrangement of the air- 
pump in connection with the condenser. 

Ans. — The suction-channel way is in connection with 
the lowest part of the condenser, in order that the water 
can be readily and completely removed from the condenser. 
It usually supports the foot-valves and all joints and! 
|valve-seat division-plates require to be fitted air-tight, 
'he barrel is generally connected to a flange or facing of 
;he suction-channel way, and it is constructed of com- 
position or cast iron with a composition sleeve pressed in 
ind bored out truly cylindrical, in order to form a smooth 



226 



QUESTIONS AND ANSWERS 



and durable working-cylinder for the buckc jr piston, 
which is kept tight against the barrel, either by water- 




Fig. 151. Sectional View op Vebticai, Single Acting Air-pump. 



grooves, or, more commonly, by packing, consisting 
vine ^r more split metallic packing rings. Sometime* 



icJ 



CONDENSERS AIR-PUMPS SEA-WATER 



227 



fibrous soft packing, held in place and compressed by a 
follower ring, is used. A stuffing box is provided in the 
top cover, through which the piston-rod or trunk, as the 
case may be, has water-tight passage. 

Ques. 578. — What kind of valves are used in air- 



GUARO 




QOfr^Q 



tmjO 




Seating 



pumps r 

Ans. — Rubber valves, 
either of hard or soft rub- 
ber, but since the introduc- 
tion of mineral oil as a 
lubricant for the engine cyl- 
inders, it has been found 
that the ordinary rubber 
valves deteriorate under its 
influence, and metal valves 
are now largely coming into 
use, especially in the navies. 
They may be made of thin 
sheet metal, are light, and 
not affected by grease, if 
cleaned occasionally, and 
will last a long time. In 
form, air-pump valves are 
either single rectangular 
flaps that lift on one edge 
igainst a curved metallic guard, or else there are a number 
)f smaller circular valves, lifting bodily from their seats, 
tnd secured to the seat by a central stud, which also carries 
metal guard above the valve. The valve-seats are usually 
dependent, being constructed of composition metal, and 




Fig. 152. 

Details op Rubber Valve, Valve- 
seat and Guard for Air-pump. 






228 



QUESTIONS AND ANSWERS 



pressed into their places. They are divided into small 
spaces by gratings, so that the unsupported area of the 
valve may not be too large. The bucket carries the 
bucket-valves, which allow the air and water to pass 
through to the delivery side. Air-pump valves are some- 
times fitted with spiral springs of bronze wire on top, to 
secure quick closing. The flap valves are clamped to the 
seat, on the stationary edge, by their curved guards. 

Ques. 579. — How is the bucket or piston of the air- 
pump actuated? 



") / Light Springs sometimes 
x^ i fitted here on bucket 

ANO fOOTVALVES 




1*ig. 153. Section of Metal Valve, Valve-seat and Guard for Air-pump. 



Ans. — Either by a solid piston-rod, or by a hollow 
trunk, made entirely of composition, or covered by a 
composition sleeve. With the piston-rod type it is neces- 
sary to have a connecting rod and guides above the top 
cover of the air-pump, while the trunk type contains the 
connecting rod bearing in the trunk, near the bucket, and 
requires no extra guides. 

Ques. 580. — What is the function of the hot well? 

Ans. — It acts as a small reservoir, for the accumula- 
tion of the discharge- water from which the feed-pumps 



CONDENSERS AIR-PUMPS SEA- WATER 



229 



draw their supply. The later vessels in the English navy 
are fitted with "feed-tanks" in which the discharge from 
the air-pumps is allowed to accumulate, and from which 
the feed-pumps draw their supply of water for feeding 
the boilers. There is a feed-tank for each engine-room, 



AttCMic* 




f | C«hau»t raon KXvWeJI 

T^y j\ i — 







f lG. 154. WORTHINGTON CENTRAL CONDENSER 1*OR A I*ARGE SVA*IOWARY PLANl % 

Showing Pumps j»nd Piping. 



md they are connected by a pipe running between the two, 
:ngine-rooms, fitted with a shut-off \alve worked fron? 
ither engine-room. These feed-tanks, are fitted with 
[lass water-gauges and zinc slabs. 



230 



QUESTIONS AND ANSWERS 



Ques. 581.— What is the function of the circulating 
puitfp In connection with the surface condenser? 




F* 155. Transverse Section op a Centrifugal Pump. B, Casing, D E. 

Curved Vanes. 



Ans. — It either forces or draws the cooling watei 
through the tubes or the body of the condenser. 



^ 



CONDENSERS AIR-PUMPS SEA-WATER £31 

Oues. 582. — What type of pump has beei, xcund to be 
best adapted to this work? 

Ans. — The centrifugal pump worked by an indepen- 
dent auxiliary engine, for the reason that the pump works 
smoothly, there are no valves, and having a separate 
engine, it can be kept working and the condensers kept 
cool when the main engines are stopped, which is not the 
case with a pump that receives its motion from the main 
engines. Another great advantage possessed by the 
independent system is, that the speed may be regulated 
so as to supply the required quantity of water. 

Ques. 583. — Describe the construction and action of 
the centrifugal circulating pump. 

Ans. — The pump consists of an impeller wheel or fan 
evolving inside a casing. The impeller and casing are 
made of gun metal, and the spindle or shaft carrying the 
mpeller is either cast of gun metal in one piece with the 
mpeller, or formed separately of forged bronze and keyed 
to it. This spindle runs in lignum-vitae bearings and is 
ubricated with water. The impeller generally consists 
}f a central web guiding the incoming water, with two 
side-plates that gradually approach each other as they 
lear the circumference and between which runs a series 
)f curved vanes. These vanes are curved away from the 
iirection of rotation as they proceed from the boss to the 
:ircumference. The water enters the central part of the 
mpeller through the inlet pipe and is thrown by the 
apidly revolving vanes outwards and around into the 
:asing which surrounds the circumference of the wheel, 
*he casing is of gradually increasing area and leads to 



232 



QUESTIONS AND ANSWERS 



the delivery pipe, through which it is forced by the cen- 
trifugal action to the condenser, where, after traversing 
the tubes, it is discharged overboard. The casing is 



tMf 




Fig. 156. Longitudinal Section op a Centrifugal Pump. A, Central W*b 
C C, Side Plates. E, Inlet. F, Discharge. 

formed in two parts to enable the impeller to be inserted 
and also to facilitate insoection. 



CONDENSERS — AIR-PUMPS SEA-WATER 233 

Ques. 584. — How is the quantity of water required to 
condense the exhaust steam of an engine determined? 

Ans. — The quantity of cooling water required for a 
condensing system depends primarily upon the system, 
whether it is surface condensing or whether the condenser 
is a jet condenser The surface condenser needs a greater 
quantity of water than does the jet condenser. This is 
due to the fact that in the surface condenser the water, 
not being mixed with the steam, can not absorb the heat 
so rapidly. 

Ques. 585. — About how much more water does a sur- 
face condenser require than is needed by a jet condenser? 

Ans. — About 15 per cent more. 

Ques. 586. — What three factors determine the quantity 
of cooling water required? 

Ans. — First, the density, temperature, and volume of 
the steam to be condensed in a given time; second, the 
temperature of the overflow and third, the temperature of 
the injection water. For instance, it may be desired to 
keep the overflow at as high a temperature as possible, for 
the purpose of feeding the boilers, or the temperature of 
the injection or cooling water varies greatly. It may 
be 35 degrees in the winter and 70 degrees in the summer. 
In the marine service the temperature of sea-water 
varies considerably, depending upon the locality, in the 
tropics the temperature of the sea-water in the summer 
being often as high as 85 degrees Fahrenheit. 

Ques. 587. — What quantity of condensing water would 
be required in a jet condenser into which the exhaust 
steam under an absolute pressure of 7 pounds is passing. 



234 QUESTIONS AND ANSWERS 

assuming the temperature of the cooling water to hi 
55 degrees and the temperature of the overflow to b< 
110 degrees? 

Ans. — In these calculations the total heat in the stearr 
must be considered. This means not only the sensible 
heat, but the latent heat also. Now in 1 pound weight oi 
steam at 7 pounds absolute pressure the total heat h 
1,135.9 heat units. The temperature of the overflow being 
110 degrees, the total heat to be absorbed from each poun< 
weight of steam in this case would be 1,135.9 
— 110 = 1025.9 thermal units. The temperature of th< 
condensing water being 55 degrees and the temperature 
of the overflow being 110 degrees, there will be 110 
degrees — 55 degrees = 55 degrees of heat absorbed b)> 
each pound of cooling water passing into and through th< 
condenser, and the number of pounds of water requirec 
to condense each pound weight of steam under thes< 
conditions will equal the number of times 55 is con- 
tained in 1,025.9, thus, 1 jV =z 18.65 pounds. Assuminj 
the steam consumption of the engine to be 17 pounds pel 
indicated horse-power per hour, then 17 X 18.65 = 317.0i 
pounds of water is required per horse-power per hour foi 
condensing purposes. 

Ques. 588. — How is the weight of cooling watei 
required per hour determined, when the steam consumptior 
per indicated horse-power per hour is not known? 

Ans. — In this case the volume of steam exhausted pel 
hour must be considered. Thus, assume the cylinder f rorr 
which the steam is exhausted to be 24 X 48 inches anc 
the revolutions per minute to be 80. The piston dis« 



CONDENSERS AIR-PUMPS SEA-WATER 



235 



placement will equal area of piston less one-half area of 
rod, multiplied by length of stroke. The area of a circle 
24 inches in diameter = 452.39 square inches. Suppose 
the piston-rod to be 4.5 inches in diameter, its area is 
15.904 square inches, one-half of which = 7.952 square 

Table No. 9 

Jet Condensing 
Quantity of Injection Water per Revolution of Engine, 
injection water 50° overflow 110° 



Low-pressure Cylinder. 


Single-cylin- 
der, Water 
per Rev. 


Two-cylinder. 

Water pei 

Rev. 


Three-cylif> 

der, Water 

per Rev. 


Lbs. 


Galls. 


Lbs. 


Galls. 


Lbs. 


Galls. 


20x36 ii 

22x36 

24x42 

26x42 

28x48 

30x48 

32x54 

34x54 

36x60 

38x60 

40x66 

44x66 

48x72 

52x72 

56x72 

60x72 

64x72 


iches 


4.2 

5.1 

7. 

8.3 
11. 
12.6 
16.2 
18.3 
22.8 
25.5 
31. 
37.5 
48.5 
57. 

66. 

75.6 
85. 


.5 
.61 
.84 
1. 

1.45 
1.52 
1.95 
2.2 
2.75 
3.07 
3 73 
4.51 
5.84 
6.89 
7,9 
9. 
10. 


3.9 

4.8 
6.6 
7.8 
10.4 
11.7 
15. 
17.0 
21.2 
23.7 
28.8 
34.8 
45. 
53.1 
61.5 
70.5 
80. 


.47 
.57 
.79 
.93 
L24 
1.41 
1.81 
2.05 
2.55 
2.85 
3.45 
4.2 
5.42 
6.4 
7.41 
8.5 
9.6 


3.6 

4.4 

6. 

7.2 

9.5 

10.8 

13.9 

15.8 

19,6 

21.9 

26.7 

32.2 

41.7 

49.2 

57. 

65.3 

74. 


.43 


u 


.53 


a 


.72 


a 


.87 


tt 


1.14 


u 


1.3 


tt 


1.68 


tt 




tt 


236 


t« 


2J4 


a 


3,2 


a 


as 


tt 


6. 


tt 


5.9 


u 


6.8 


tt 


7,8 


tt 


as 







(Table No. 9. 
troit, Mich. ) 



-From Book on Compound Engines. By James Tribe, Dd- 



inches. The effective area of the piston is therefore 
452.39 — 7.952 = 444.4 square inches and the piston 
displacement equals 444.4 X 48 = 21,332.64 cubic inchfc*. 
It is necessary in this calculation to express the total 
volume of steam exhausted per minute in cubic feet, 
therefore 21,332.64 ■*• 1.728 (number of cubic inches in a 



236 QUESTIONS AND ANSWERS 

cubic foot) gives 12.34 cubic feet of piston displacement, 
and the engine running at a speed of 80 revolutions per 
minute will send into the condenser a volume of steam 
equal to twice the piston displacement multiplied by the 
number of revolutions per minute, expressed thus: 12.34 
X 2 X 80 = 1,974.4 cubic feet per minute. Assuming the 
absolute pressure of the exhaust to be 7 pounds per 
square inch, the weight of 1 cubic foot of steam at 7 
pounds absolute is .0189 pounds and the total weight of 
steam exhausted per minute would be 1,974.4 X .0189 = 
37.3 pounds, and if 18.65 pounds of water is required to 
condense 1 pound weight of steam at 7 pounds absolute, 
the total weight of water required per mirute in this case 
would be expressed as follows: 37.3 Y 18.65 = 695.8 
pounds, or per hour 695.8 X 60 = 41,74$ pounds, equal to 
5,029 gallons. 

Ques. 589. — What quantity of condensing water would 
be required in a surface condenser, assuming the condi- 
tions to be the same as described in the answer to question 
587? 

Ans. — A surface condenser requires about 15 to 
20 per cent more condensing water \han a jet condenser 
does. It was seen in the answer referred to that 18.65 
pounds of water were required to condense 1 pound 
weight of steam, therefore the quantity of water requirec 
by the surface condenser woul'i 'be about 22 or 23 pounds 
for each pound of steam. 

Ques. 590. — What provision is made on board oi 
vessels for obtaining a snp^V of water for the condenseri 
and for other p'rpoaei? 



CONDENSERS — AIR-PUMPS — SEA- WATER 



237 



Table io 
Areas and Circumferences of Circles. 



Diam. 



•25 
• 5 
I.O 

1.25 

1-5 

2 

2.25 

2.5 

3 

3.25 

3-5 

4 

425 

4.5 

5 

5.25 

5.5 

6 

6.25 

6.5 

7 

7.25 

7-5 
8 

8.25 

8.5 

9 

9-25 

9-5 
10 

10.25 
10.5 
11 
11.25 

11- 5 

2 

12.25 
a-5 
3 
325 

3-5 

4 

4.25 

4.5 
5 

5 25 



Area. 



.049 
.1963 

.7854 
1. 2271 
I.7671 
3.I4I6 
3.9760 
4.9087 
7.0686 

8.2957 
9.6211 
12.566 
14.186 
15.904 

I9-635 
21.647 
23.758 
28.274 
30.679 
33.183 
38.484 
41.282 
44.178 
50.265 
53.456 

56.745 
63.617 
67.200 
70.882 
78.540 
82.516 
86.590 

95.033 

99.402 

IO3.869 

II3.O97 

117.859 
122.718 
132.732 
137.886 
143.130 
153.938 
I59-485 
165.130 

176.715 
182.654 



Circum. Diam. Area 



.7S54 
I.5708 
3.I4I6 
3.9270 
4.7124 
6.2832 
7.0686 
7.8540 
9.4248 
IO.210 

IO-995 
12.566 

13.351 
14.137 

I5.708 
16.493 
17.278 
18.849 

I9-635 

20.420 

21.991 

22.776 

23.562 

25.132 

25.918 

26.703 

28.274 

29.059 

29.845 

3I.4I6 

32.201 

32.986 

34.557 

35-343 

36.128 

37.699 

38.484 

39- 270 

40. 840 

41.626 

42.411 

43.982 

44» 767 

45.553 
47.124 

47-909 



15.5 
16 

16.25 

16.5 

17 

17.25 

17.5 

18 

18.25 

18.5 

19 

19.25 

19-5 

20 

20.25 

20.5 

21 

21.25 

21.5 
22 

22.25 
22.5 

23 

23.25 

23.5 

24 

24.25 

24.5 

25 

25.25 

25.5 

26 

26.25 

26.5 

27 

27.25 

27.5 

28 

28.25 

28.5 

29 

29.25 

29.5 

30 

30.25 

30.5 



i.692 
201.062 

207.394 
213.825 
226.980 
233.705 
240.520 

254-469 
261.587 
268.803 
283.529 
291.039 
298.648 
314.160 
322.063 
330.064 
346.361 
354.657 
363.051 
380.133 
388.822 
397.6o8 
415.476 
424.557 
433.731 
452.390 
461.864 
471.436 
490.875 
500.741 
510.706 
530.930 
541.189 
55L547 
572.556 
83.208 
593.958 

615.753 
626,798 

637.941 
660.521 
671.958 
683.494 
706.860 
718.690 
730.618 



Circum. Diam 



48.694 
50.265 
5L05I 
51.836 
53.407 
54.192 
54.978 
56.548 

57.334 
58.II9 
59.690 

60.475 
61.261 
62.832 
63.617 
64.402 
65.973 
66.759 
67.544 
69.115 

69.900 
70.686 
72.256 
73.042 
73.827 

75.398 
76.183 
76.969 
78.540 
79.325 
80.110 
81.681 
82.467 
83.252 
84.823 
8 5. 60S 

86.394 
87.964 
88.750 

89.535 
91.106 
91.891 

92.677 
94.248 

95.033 

95.8i8 



31 

31.25 
31.5 

32 
32.25 

•33 

33.25 

33-5 

34 

34.25 

34-5 

35 

35.25 

35.5 

36 

36.25 

36.5 

37 

37.25 

37.5 

38 

38.25 

38.5 

39 

39-25 

39-5 

40 

40.25 

40.5 

4i 

41.25 

41.5 
42 

42.25 

42.5 

43 

43-25 

43.5 

44 

44.25 

44.5 

45 

45.25 

45-5 
46 

46.25 



Area. Circum, 



754.769 
766.992 

799.313 

804.249 

816.86 

855.30 

868.30 

881.41 

907.92 

921.32 

934.82 

962.II 

975.90 
989.80 
1017.8 
1032.06 
1046.35 
1075.21 
1089. 79 
1104.46 

1134.11 
1149.08 

1164.15 

1 [94.59 
1209.95 

1225.42 

1256.64 

1272.39 

1288.25 

1320.25 

1336.40 

1352.65 

1385.44 

1401.98 

1418.62 

1452.20 

1469.13 

1486.17 

1520.53 

1537.86 

1555.28 

1590.43 
1608.15 
1625.97 
1661.90 
1680.01 



97.389 
98.175 
98.968 
100. 53 
101.31 
103.67 

104.45 
105.24 
106.81 
107.60 
108.38 
106.95 
110.74 
in. 52 
113.09 
113.88 
114.66 
116.23 
1 17.01 
117.81 
119.38 
0.16 

120.95 

122.52 

123.30 

124.00. 

125.66 

126.44 

127.23 

128.80 

129.59 

130.37 

131.94 

132.73 

133.51 

135.08 

135.87 

136.65 

138.23 

1 39- 01 

139.80 

141.37 

142.15 

142.94 

144.51 
145.29 



838 



QUESTIONS AND ANSWERS 



Table lO—Coramued. 



Diam. 


Area. 


Circum. 


Diam. 


Area. 


Circum. 


Diam. 


Area. 


Circum.. 


46.5 


l6g8.23 


146.08 


62.25 


3043.47 


195.56 


7S 


4773.37 


245.04 


47 


1734.94 147.65 


62.5 


3067. 96 


196.35 


7S.25 


4809,05 


245.83 


47.25 


i753-*5 


148.44 


63 


3117.25 


197.92 


73. 5 


4S39.83 


246.61 


47.5 


1772.05 


149.22 


63.25 


3142.04 


198.71 


79 


4901. 6S 


248.19 


4 3 


1809.56 


150.79 


63.5 


3166.92 


I99.50 


79^3 


4932.75 


24S.97 


48.25 


1828.46 


I5L58 


64 


3216.99 


20I.06 


79.5 


4963.92 


249.76 


48. 5 


1847.45 


152.36 


64.25 


3242.17 


201.85 


80 


5026.56 


25L33 


49 


1885.74 


153-93 


6+5 


3267.46 


202. 63 


80.5 


5089. 5S 


252.90 


49.25 


1905.03 


154.72 


65 


3318.31 


204.20 


81 


5i53.oo 


25447 


49-5 


1924.42 


I55.50 


65.25 


3343.83 


204.99 


81.5 


5216.S2 


256.04 


50 


1963.50 


157.08 


65.5 


3369.56 


205.77 


82 


5281.02 


257.61 


50.25 


1983.18 


157.86 


66 


3421.20 


207.34 


82.5 


5345-62 


259.18 


5o.5 


2002.96 


153.65 


66.25 


3447.16 


20S.13 


83 


5410.62 


260. 75 


51 


2042.82 


160.22 


66.5 


3473.23 


208.91 


83.5 


5476.00 


262.32 


51.25 


2062.90 


161.00 


67 


3525.66 


210.49 


84 


554L78 


263.89 


51.5 


2083.07 


161.79 


67.25 


3552.01 


211.27 


84.5 


5607.95 


265.46 


52 


2123.72 


163.36 


67.5 


357S.47 


212.06 


85 


5674.51 


267.04 


52.25 


2144.19 


164.14 


63 


3631.68 


213.63 


85.5 


5741-47 


268.60 


52.5 


2164.75 


164.19 


6S.25 


3658.44 


214.41 


86 


5808.81 


270.17 


53 


2206.18 


166.50 


68.5 


36S5.29 


215.20 


86.5 


5376.55 


27L75 


53.25 


2227.05 


167.29 


69 


3739.28 


216.77 


87 


5944.66 


273.32 


53.5 


2248.01 


168.07 


69.25 


3766.43 


217.55 


87.5 


6013.21 


274.89 


54 


2290.22 


169.64 


69.5 


3793.67 


218.34 


88 


6082.13 


276.46 


54.25 


2311.48 


170.43 


7o 


3S48.46 


219.91 


8S.5 


6151.44 


278.03 


54-5 


2332.83 


171. 21 


70.25 


3875.99 


220.70 


89 


6221.15 


279.60 


55 


2375.83 


172.73 


7o.5 


3903.63 


221.48 


89.5 


6291.25 


281.17 


55.25 


2397.48 


173.57 


7i 


3959.20 


223.05 


90 


6371.64 


2S2.74 


55-5 


2419.22 


174.35 


71.25 


39S7-I3 


223.84 


90.5 


6432.62 


284.31 


56 


2463.01 


175.92 


71.5 


4015.16 


224.62 


9i 


6503.89 


2S5.88 


56.25 


2485.05 


176.71 


72 


4071.51 


226.19 


91.5 


6573.56 


287.46 


56.5 


2507.19 


177.5 


72.25 


4099.83 


226. 9S 


92 


6647.62 


289.03 


57 


2551.76 


I79.07 


72.5 


4128.25 


227.75 


92.5 


6720.07 


290.60 


57.25 


2574.19 


179.85 


73 


4135.39 


229.34 


93 


6792.92 


292.17 


57.5 


2596.72 


ISO.64 


73.25 


4214. 11 


230.12 


93.5 


6866.16 


293.74 


58 


2642. oS 


I82.2I 


73.5 


4242.92 


230.91 


94 


6939.79 


295.31 


58.25 


2664.91 


I82.99 


74 


4300.85 


232.48 


94-5 


7013.81 


296.88 


58.5 


2687.83 


183.73 


74-26 


4329.95 


233.26 


95 


7088.23 


298.45 


59 


2733-97 


185.35 


74.5 


4359.16 


234.05 


95.5 


7163.04 


300.02 


59-25 


2757.19 


IS6.I4 


75 


4417.87 


235.62 


96 


7238.25 


301.59 


59-5 


2780.51 


186.92 


75.25 


4447.37 


236.40 


96.5 


7313.80 


303.16 


60 


2S27.44 


183.49 


75.5 


4476.97 


237.19 


97 


7389.81 


304.73 


60,25 


2851.05 


189.28 


76 


4536.37 


238.76 


97-5 


7466.22 


306.30 


60.5 


2874.76 


I9O.06 


176.25 


4566.36 


239-55 


98 


7542.89 


307.88 


61 


2922.47 


I9I.64 


76.5 


4596.35 


240.33 


98.5 


7620.09 


309.44 


61.25 


2946.47 


192.42 


77 


4656.63 


241.90 


99 


7697.70 


311.02 


61.5 


2970.57 


193.21 


77 25 


4686.92 


1242.69 


99.5 


7775.63 


312.58 


62 


3019.07 


194.78 


77-5 


4717.30 


243.47 


100 


7854.00 


314.16 



CONDENSERS AIR-PUMPS SEA-WATER 



239 



Ans. — All holes in the hull of a ship below the water- 
line for the supply or discharge of condensing wa- 
ter, or for any other purpose, are fitted with valves 
having long spindles 
which are brought inside 
the vessel through stuff- 
ing boxes, in order that 
the valves may be worked 
from inboard. The cir- 
culating pumps take 
their suction from a 
large screw-down inlet 
valve on the bottom of 
the ship, while the dis- 
charge is through simi- 
lar valves on the ship's 
side. 

Ques. 591.— What 
type of valve is largely 
used for this purpose? 

Ans. — The Kingston 
sea-valve. Strainers are 
placed over all inlets, to 
prevent the entrance of 
weeds and other impuri- 
tieSc 

Fig. 157. Sea-valve. 




A 



CHAPTER VIII 

AUXILIARY MACHINERY AND FITTINGS 

Oues. 592. — Besides the air and circulating purnps, 
what other pumps are required in well-equipped steam 
plants, or aboard steam-ships? 

Ans. — Boiler feed-pumps, fire service, pumps for 
hydraulic elevators, and other service requiring water- 
pressure, and in addition, on ship-board, pumps are 
required for emptying the bilges and tanks and for supply- 
ing water for washing the decks, evaporator service and 
for sanitary purposes. 

Ques. 593. — Is there a special pump provided for each 
sei vice? 

Ans. — Not in all cases, but one pump may be con- 
nected in such a manner as will permit of its being used 
alternately for several different purposes. However, a 
special pump is, or at least should always be provided for 
teeding the boilers. Also a special bilge-pump is usually 
supplied, for the reason that it handles very dirty water, 
that should not be passed through any other pipe system. 
In small vessels one pump (the donkey) usually serves for 
nearly all purposes, including auxiliary boiler-feed, and 
on Western river steamers an independent pump (the 
doctor) having a steam-cylinder and walking-beam, drives 
a system of pumps for feed, fire and bilge-pumping 
service. 

240 



AUXILIARY MACHINERY AND FITTINGS 



241 



Ques. 594. — What special features should appertain 
to the boiler feed-pump? 

Ans. — It should be simple, durable, of great strength 
and ample capacity to insure regular and reliable service 
under the most severe conditions. It is always best to 
have the main and auxiliary feed-pumps duplicates of 
each other if possible, for the reason that in cases of 

emergency the different 
parts are interchangeable. 
In the marine service the 
main feed-pump draws its 
supply of water from the 
hot well, feed-heater or the 
feed-tank, as the case may 
be. The auxiliary or du- 
plicate feed-pump may be 
arranged so as to draw 
from either of these sources,, 
and also from the sea, thus 
making provision for 
emergency. 

Ques. 595. — W here 

should the feed-pumps be 

located? 

Ans. — As near to the boiler-room as possible, in order 

that the engineer in charge of the boilers may have fult 

control of the feed-water supply. On board of vessels, 

when the feed-pump is worked from the main engine, the 

auxiliary, or injector is usually placed in the stoke-holcL 

Ques. 596.— What type of boiler feed-pump has 




FlG. 158. The Worthington Boiler- 
feed Pump, Admiralty Pattern. 
For 250 Pounds Pressure. 



242 QUESTIONS AND ANSWERS 

been found to be the most reliable for all kinds of 
service? 

Ans. — The double acting steam-pump, working inde- 
pendently of all other machinery. The horizontal variety 
is principally used for land service, while on board steam 
vessels the vertical type is preferred, for the reason that 
it occupies less floor space. In both the horizontal and 
vertical types, the water valve-chambers have removable 
covers, allowing a ready access to the valves and valve- 
seats. The steam-valves of these pumps are actuated in 
various ways. In the duplex variety, which consists of 
two pumps combined into one, the steam-valve of one 
side is moved from the piston-rod of the other, and vice 
versa, while with a pnmp having but a single steam-cylin- 
der, the steam-valve is worked by a tappet action from 
<ts own piston-rod. 

Ques. 597. — What two varieties of feed-pumps are 
largely in use on ocean steamers? 

Ans. — The Weir vertical double-acting steam-pump 
and the Belleville, which is built either vertical or horizon- 
tal. In the Weir pump the water-valves are a series of 
small cones milled out of solid metal and give a large 
area of opening with a slight lift. The steam-valve 
arrangement of the Weir pump is rather complicated and 
requires to be maintained in perfect condition, to insure 
good service. It consists of a main valve for distributing 
steam to the cylinder and an auxiliary valve for distribu- 
ting steam to work the main valve. The main valve moves 
horizontally from side to side, being driven bv *fc— ~ 
tdmitted and exhausted from each end alternatelv. The 



AUXILIARY MACHINERY AND FITTINGS 



243 



auxiliary valve is actuated by a lever with a fixed fulcrum 
worked by the piston- 
rod of the pump. This 
auxiliary valve moves on 
a flat face on the back of 
the main valve and in a 
direction at right angles 
to the latter. Both the 
main and auxiliary valves 
are simply slide valves, 
but the main valve is half 
round, the round side 
working on the corre- 
spondingly shaped cylin- 
der port-seat, while the 
back of the valve is flat 
and forms the seat for 
the auxiliary valve. Both 
ends of the main valve 
are lengthened, so as to 
project beyond the port 
face and are turned cylin- 
drical, with flat ends. 
Caps are fitted on each 
of these ends, forming 
cylinders which are 
closed at the mouths by 
the flat ends of the main 
valve, which act as pis- 
tons, the length of stroke F,G ' ™uZ££s£fi£ na 




1 



244 QUESTIONS AND ANSWERS 

that the piston can make being the full travel of the 
valve. The auxiliary valve-seat has three ports, the 
center one being the exhaust and the two side ports being 
steam-passages leading through the piston ends of the 
main valve. The right-hand cylinder port-passage is led 
through the left-hand end of the piston and the left-hand 
passage leads to the other end. These ports admit steam 
to the two small caps or cylinders at each end of the valve 
alternately, by which it is thrown from side to side. 
Besides the ports already referred to, there are two 
other ports formed on the auxiliary valve-seat leading to 
and corresponding to two ports on the half-round seat of 
the main valve. These ports are for the purpose of 
admitting steam to the top and bottom of the main cylin- 
der, and are arranged on the auxiliary valve-seat to cut 
off steam before the end of the stroke, and so reduce the 
speed of the piston, but the expansion chambers at each 
end of the main valve are fitted with by-passes to admit 
Jteam for the full stroke when so desired. This may be 
necessary when starting the pump, as then the water- 
cylinder may be full of water. These by-passes are formed 
by notches cut in the edges of the caps and may be opeied 
or closed by turning the caps by means of spindles pro- 
vided at each side of the valve-chest, and thus give a 
definite cut-off. There are separate by-passes for the up 
and down strokes, and the silent working of the pump 
depends upon the proper adjustment of these by-passes. 

Ques. 598. — Describe the action of the Belleville feed- 
pump. 

Ans. — The pump is double-acting, having an ordinary 



AUXILIARY MACHINERY AND FITTINGS 



245 



flat slide-valve without lap, worked by a curved lever, 
which is moved at each end of the stroke, by a projection or 
lug on the piston-rod. The steam-ports are arranged at 
each end of the cylinder in such a manner as to admit the 
steam uniformly all around the cylinder circumference, 
and not at the top only, which prevents bending forces 
on the rod. The steam-pressure remains constant, 
therefore, until near the end of the stroke, when the pro- 
jection strikes the valve-lever and commences to close the 



LONGITUDINAL SECTION 




Fig. 160. Beu,Evii,i,e Feed-pump. 



steam-valve, so that the steam-pressure falls and the 
motion would cease, but for special provisions. Before 
the piston can commence the return stroke, it is necessary 
that the valve should not only be closed but pushed suffi- 
ciently far over to reopen for steam on the other side. 
To enable the steam already in the cylinder to complete 
the stroke and throw the valve over to the opposite side, 
an orifice is provided at each end of the water-cylinder, 
closed by levers and communicating with the suction- 
chamber, so that when the water-piston nears the end of 



246 



QUESTIONS AND ANSWERS 



its stroke, it strikes one of these levers and opens the orific 
to the suction-chamber, thus causing the pressure in th 
water-cylinder to fall, and the steam, although cut off 
is enabled by its expansive force to push the piston to th 
end of the stroke and reverse the valve. Motion then 
begins in the opposite direction. The water-valves are a 
series of small valves, generally eight in number, at each 
end, four for suction and four for discharge. Small holes 
about tV inch in diameter, are made through the levers into 




VX»v»>w>»t»»/M»rrr7K 



rao ountr 




STCAkt QUVLtT 



Fig. 161. Kirkaldy's Feed-heater. 

• 

the passage leading to the suction chamber, so that a 
small quantity of water is always escaping from the water- 
cylinder, which causes the pump to keep slowly in motion, 
even when the feed-valves on the boilers are closed. 

Ques. 599. — Are feed-water heaters much in use in 
the marine service? 

Ans. — They are largely used in the mercantile service, 
and results justify their adoption. 

Ques. 600. — Describe the construction and operation 
of Kirkaldy's feed-heater. 



AUXILIARY MACHINERY AND FITTINGS 



247 



Ans. — It is constructed along lines similiar to a sur- 
face condenser, having tubes rolled into tube-plates in the 
ordinary manner, the whole surrounded by an outside shell, 
leaving spaces at each end between the tube-plates and 
end-covers. The feed-water does not mix with the 
heating steam, but is drawn through the tubes, on thej 



mm mm* 




Fig. 162. Weir's Feed-heater and Regulator. 



outside of which is the steam, which is usually the exhaust 
from various auxiliary engines, or it may be drawn from 
the boilers. By-pass valves are fitted, so that when 
necessary the feed-water can be passed direct, without 
passing through the heater. 



248 



QUESTIONS AND ANSWERS 



Ques. 601. — Describe the construction and operation 
of Weir's feed-heater and regulator. 

Ans. — It takes steam from the final receiver of the 
engine after it has done most of its work. The steam 
enters the heating chamber through a circular perforated 
ring and there mixes with the cold feed-water, which is 
admitted through the spring-loaded valve on the cover. 




Fig. 163, The Harris Grease Filter. 

The heated water falls to the bottom of the heater s from 
whence it is removed by the feed-pump. A galvanized 
iron float is fitted to the bottom of the heater, which 
communicates by means of levers with the steam-valve 
leading to the feed-pump, thus keeping the water-level 
constant in the heater and preventing the pumps from 
drawing air. 



AUXILIARY MACHINERY AND FITTINGS 249 

Ques. 602. — What provision is made on board steam- 
vessels for the prevention of oil or grease passing into 
the boilers along with the feed-water? 

Ans. — Numerous types of grease-filters are in use- 
In the Harris grease-filter the feed-water is caused to pass- 
through a series of gratings, on each of which is fitted 
one or two sheets of filtering material, consisting of 
toweling or flannel, supported by wire gauze. When the- 
cloths become dirty they are cleaned by a steam jet, and 
washed off by a reverse current of water. 

Ques. 603. — What is the object of placing a governor 
on an engine? 

Ans. — To maintain regularity of speed of the engine 
when the load is varied from any cause. 

Ques. 604. — Upon what principle do the most of the 
jovernors for land engines operate? 

Ans. — Upon the principle of centrifugal force causing 
wo balls or weights, each suspended or attached to a lever 
iwinging on a fulcrum, fixed near the top of a vertical 5 
evolving spindle, to fly outward as the speed increases; 
,nd the force of gravitation which acts in the opposite 
lirection as the speed decreases. The outward movement 
f the balls or weights is utilized to either close the throt- 
le or shorten the point of cut-off, while the inward move- 
nent has the opposite effect. 

Ques. 605. — Are governors required on marine en- 
p ines? 

Ans. — They ere, for the reason that in a marine engine 
onsiderable diminution in resistance may ensue in rough 
r stormy weather, from the pitching motion of the vessel* 



250 QUESTION^ AND ANSWERS 

which causes the propellers to rise partly out of the water, 
thus causing what is technically known as "racing of 
the engines." 

Ques. 606. — Is the centrifugal type of governor suit- 
able for marine service? 

Ans. — It is not, for the reason that the forces acting 
upon the balls or weights would be affected by the motion 
of the ship and the action would be irregular. Other 
forms of governors for marine engines are in use with 
various degrees of success, but all, or nearly all of them, 
possess the one defect of requiring an increased speed of 
the engine to cause them to act, and even then their action 
is sluggish, the throttle-valve being generally closed after 
the racing is over. 

Ques. 607. — What type of marine governor is likely 
to prove the most successful in marine service for the 
prevention of "racing?" 

Ans. — A governor that acts by variations of pressure 
at the stern of the vessel near the propeller, and not 
from engine-speed variations. Racing being caused by 
diminished immersion of the propeller, it is accompanied 
by a diminution of pressure of water at that part, which 
can be utilized to actuate the throttle-valve. Such gov- 
ernors may therefore anticipate and prevent any increase 
of speed due to the above cause, although they would have 
no effect in case of a serious increase of speed, due to 
such an accident as a broken shaft or propeller. 

Ques. 608. — Describe Dunlop's governor, which is of 
the latter type. 

Ans.-— It consists of a sea-cock at the stern of the 



AUXILIARY MACHINERY AND FITTINGS £51 

ship, opening into an air-vessel or air-chamber, so con- 
structed that, by opening the sea-cock, water flows into 
the air-vessel and compresses the air contained therein to 
a pressure equivalent to the head of water outside the 
ship. From the top of the air-chamber a pipe is led to 
the under side of an air-tight elastic diaphragm, forming 
Dart of an apparatus in the engine-room. On the upper 
side of the diaphragm is a spiral spring, with means of 
adjusting its compression to balance the air pressure 
)elow the diaphragm. From the center of the diaphragm 
i connection is made to the slide-valve of a small steam- 
:ylinder so constructed that its piston moves in exact 
iccordance with the movements of the diaphragm. This 
>team-piston is connected by suitable gear to the throttle- 
valve of the engine whose speed is to be controlled. The 
iction is as follows: The sea-cock being open, any varia- 
;ion of head of water outside the ship is accompanied by 
in inflow or outflow of water through it and consequently 
i variation in the pressure of the air contained in the air- 
camber, and also under the diaphragm of the engine-room 
ipparatus, causing the diaphragm to move through such 
>art of its travel as is requisite to enable the compression 
)f spring and the air-pressure to balance each other again, 
ivery movement of the diaphragm is followed by a 
torresponding movement of the governor steam-piston, 
ind consequently of the throttle-valve of the engines 
inder control, the time taken between the variation in 
he head of water at the stern of the ship and the moving 
>f the throttle-valve being practically nothing. The 
:overnor therefore anticipates any increase in the speed 



252 



QUESTIONS AND ANSWERS 



of the engines due to the propeller rising out of the wate 
and does not depend upon a variation in speed of th< 
engines to be controlled, before it acts. By adjusting th 
balance between the spring and the air-pressure under th 
diaphragm the diaphragm begins to fall and the throttle 
valve to close, when the tips of the propeller-blades ris 




^ 



B 



P/PELEO TO 
C THE BOTTOk 
OF A/R-TlGHr 

Diaphragm 



A 

A/r Vessel 

AT 

Stern of Sn/p 



Engine Room 
Apparatus 




Sea Cock fir teo here 



Fig. 164. Dunlop's Governor. 

to any desired distance above the surface of the water 
The air-vessel should be fitted as far aft in the screw-tun« 
nel as possible, the hole through the side of the vesse 
being placed about one-fourth the diameter of th* 
propeller below the level of the center of the shaft. Th< 
reports of the action of this governor in the mercantile 



AUXILIARY MACHINERY AND FITTINGS 



253 



narine are very satisfactory. It is fitted in the "Cam- 
>ania," "Paris," and many other vessels. 

Ques. 609. — How is the fresh water needed on board 
hip for drinking, washing, culinary purposes, and for 
naking up for the waste of feed-water for the boilers and 
or various other purposes, obtained? 




Hr*r?*Mit ftta 



Normandy's Evaporator. 



Ans. — By means of evaporators and distillers. The 
vaporators are really small boilers, with heat obtained 
rom steam passing through tubes, while the water to be 
vaporated surrounds the tubes. There is no coal used 
i these boilers, the steam being obtained from the main 



254 QUESTIONS AND ANSWERS 

boilers. The vapor produced is conducted to the distillii 
apparatus, where it is condensed into fresh drinkin 
water, and a portion of it goes to the condensers for tl 
purpose of making up the deficiency of boiler feed-watei 
The condensed primary steam is returned to the boilers. 

Ques. 610. — Describe Normandy's evaporator. 

Aps. — In this type of evaporator the tubes are a 
straight and rolled into tube-plates at their ends. Th 
steam from the main boilers enters these tubes through 
pipe at the top and evaporates the surrounding sea-wat< 
contained in the shell, and is itself condensed and pass< 
out through the bottom, returning to the boilers. Th 
vapor generated outside the tubes is conveyed by a vah 
and pipe, either to the auxiliary condenser for feed-wat( 
make-up, or else to the distilling condensers for th 
production of drinking water. The resulting scale 
deposited in the evaporator, from whence it is cleaned 
intervals. The sea-water for the evaporator is supplie 
by a pump. It takes its supply from a feed-box contain 
ing a float which maintains a constant level in the feed 
box. 

Ques. 611. — Describe Normandy's condenser. 

Ans. — The steam from the evaporator enters the con 
denser through a pipe at the top and passes downward 
through two series of tubes, the upper set being th 
condensing and the lower the cooling tubes. These tube 
are surrounded by a casing, which is kept filled with col( 
lea-water that enters at the bottom and flows out at th 
top through an overflow pipe that is connected to tto 
casing at a point a short distance below the top and 



AUXILIARY MACHINERY AND FITTINGS 255 

then carried to some distance above the top of the cham- 
ber before discharging overboard. By means of this 
arrangement the hottest sea-water is not discharged over- 
board, but instead may be used in the evaporator, in 
connection with the condenser, and thus promote economy 
of evaporation. An air-pipe is fitted to allow the air 
evolved from the condensing water in the casing by heat 
to pass into the overflow pipe leading to the sea. The 
condensed water rises from the lower chamber through a 
stand-pipe connected at the bottom and overflows from 
this pipe into and down another pipe leading to the suction 
of a small steam donkey pump, which pumps it into test- 
tanks, from whence it flows by gravity to the water-tanks 
in the hold of the vessel. By this arrangement the cool- 
ing tubes of the condenser are always kept full of water 
and the fresh water is drawn off cold. 

Ques. 612. — On vessels carrying cargoes of fresh 
meat and other perishable articles that are affected by 
the heat, what provision is made for their preservation? 

Ans. — Various types of refrigerating machinery are in 
use, some using the cold-air system, others the carbonic- 
acid system, and a few of the smaller ships are fitted with 
machines for making ice only. 

Ques. 613. — Describe the cold-air system. 

Ans. — The machine consists of a tandem compound 
engine having piston slide-valves both on the same valve- 
rod and worked by a single eccentric. This engine 
supplies the motive power of the apparatus. Two air- 
ylinders, one called the compressing cylinder and the other 
one the expanding cylinder, are placed side by side and in 



256 QUESTIONS AND ANSWERS 

line with the low-pressure cylinder of the engine. These 
air-cylinders are double acting, the pistons receiving their 
motion from the crank-shaft driven by the engine. The 
action of the device is simple and is as follows: The 
revolving shaft, through the medium of connecting rods 
and guides, moves the pistons up and down. Air is 
drawn into the compressing cylinder through inlet-valves 
from the surrounding atmosphere or from the cold room. 
It is compressed on the return stroke of the piston and 
passes into the cooling chamber, which is constructed 
similar to a surface condenser, having a pump to circu 
late the cooling sea-water through it. The work done thus 
far appears as heat in the air and this heated air, passing 
through the tubes of the air-cooler, is cooled by the cir- 
culating water and is then led to the valve-chamber of the 
expanding cylinder. The valve arrangement of this 
cylinder consists of a slide-valve and an expansion valve 
working on the back of the slide-valve. This arrange- 
ment supplies a means of sharply cutting off the inlet of 
air when it enters the expanding cylinder. The compress- 
ing cylinder is provided with a water-jacket through 
which the circulating pump delivers the cooling water op 
its way from the air-cooler to the sea. The slide-valve* 
are so arranged in the expanding cylinder that when the 
proper quantity of air is admitted the supply is cut off 
and during the remainder of the stroke the air expands 
and therefore does work on the piston and heat is 
expended in the process in exactly the converse manner 
to the generation of heat in the compressing cylinder, 
As, however, the air has been deprived of its surolus beat 



AUXILIARY MACHINERY AND FITTINGS 



251 




CM} ,_, (M) „ 

— n — n 



CONOEHSER 




Pic 165. Cold -£ir System oe Refrigeration. 



258 



QUESTIONS AND ANSWERS 



in the cooling chamber, the heat equivalent of the work it 
does in the expanding cylinder is absorbed from itself and 
the result is a considerable lowering of its temperature. 
This cold air is then exhausted through the orifice of the 
slide-valve in the usual manner, and conducted first to the 




Brine to col 4 

chamber. 



Fig. 166. Carbonic-Acid System of Refrigeration. 

3 'snow-box" a small accessible chamber in which the snow 
formed from the moisture is deposited, and from thence to 
the cold chamber, in which the supply of meat or provi- 
sions is kept and where it displaces air of a higher tem- 
perature. The refrigerating chamber is insulated by 
lagging its bulkheads, ceiling, and floor with silicate cottuk 



AUXILIARY MACHINERY AND FITTINGS 259 

or other non-conductor, a teak lining being fitted o\ cr 

this to form the inside surface. 

Ques. 614. — Describe the carbonic-acid system. 

Ans. — A very successful and efficient device is the 
carbonic-anhydride system of Messrs. J. & E. Hall, in 
which carbonic anhydride is passed round continually in 
the circuit. The apparatus consists of three parts: a 
compressor, a condenser, and an evaporator. The com- 
pressor draws in heated and expanded gas from the 
evaporator and compresses it. The compressed gas then 
passes to a condenser, consisting of coils in which the 
warm compressed gas is cooled and liquefied by reduction 
of temperature caused by the action of the cooling sea- 
water. From the condenser the cool liquid carbonic 
anhydride is conveyed into the evaporator consisting of 
coils, where it vaporizes and expands, absorbing heat in 
the process and cooling the surrounding brine, which is 
in contact with the coils. This cold brine is circulated 
by a small pump to the refrigerating chamber, where it 
is conducted through a long series of rows of cooling 
pipes, termed "grids/ y which are placed at the roof of 
the chamber. The cold-brine "grids" in this position set 
up a circulation of air, the cold air descending and being 
replaced by air not so cold, which is cooled in its turn. 
Any moisture in the air is condensed on the "grids" and 
appears as frost on the pipes. The theory of the action 
of this system is as follows : Under atmospheric pressure 
the liquid C0 2 would evaporate at a temperature of 
120 degrees Fahrenheit below zero, but its temperature of 
evaporation rises with the pressure, in a similar manner as 



260 QUESTIONS AND ANSWERS 

water. At a pressure of 500 pounds per square inch it 
boils at a temperature of 30 degrees Fahrenheit so that 
cold water may be used to supply the heat for boiling it. 
The pressure in the evaporator is therefore regulated to 
the required temperature of the cooling water, so that a 
considerable pressure is necessary in the evaporator. The 
compressor draws the gas from the evaporator and com- 
presses it to the liquefying pressure, the heat due to the 
compression being absorbed by the cooling water in the 
condenser coils and the gas in these coils becomes liquid 
before its exit. The liquid is then boiled in the evapora- 
tor coils, cooling the surrounding brine by the heat 
absorbed during evaporation. The compressor gland is 
made tight by cupped leathers with glycerine forced 
between them at a higher pressure than that in the com- 
pressor, so that no escape of gas can take place. The 
carbonic anhydride is supplied in steel cylinders to 
replenish the supply. 

Ques. 615. — What types of dynamos are used on board 
ships for generating electric current for internal illumi- 
nation and for working search-lights and motors? 

Ans. — They are usually of the two-pole type, direct 
driven and carried on an extension of the engine-bed. 
They have drum armatures and the field-magnets are 
compound wound, to give a constant pressure of 80 or 
100 volts for any current from zero to the maximum, 
while the speed is maintained constant. The usual speed 
is 320 revolutions per minute. The machines are con- 
nected to a switchboard located in a central position, from 
which the current is distributed to the various circuits for 



AUXILIARY MACHINERY AND FITTINGS 



261 



lighting, motors, etc. This board is so arranged that a 
circuit can be quickly changed from one machine to 
another, but no circuit can receive current from two 




262 QUESTIONS AND ANSWERS 

machines at the same time. The most recently fitted 
dynamos for the marine service are of the iron-clad type, 
the field coils and the armature being almost entirely 
surrounded by iron, to reduce to a minimum the leak- 
age of magnetic lines of force which may affect com- 
passes or chronometers in the neighborhood. 

Ques. 616. — How are these dynamos usually driven? 

Ans. — By vertical two-cylinder engines, generally 
compounded, although in some ships, where the steam- 
pressure is low, the engines are simple. All parts are 
carefully balanced and a heavy fly-wheel is fitted on the 
engine-shaft, at the dynamo end, which conduces to steady 
running. The speed is regulated by an isochronal governor 
fitted on the shaft. 

Ques. 617. — Describe the construction of the arma- 
ture. 

Ans. — The armature-core is built up of thin disks of 
soft iron slipped over metal sleeves, which are keyed on 
the shaft. The disks are insulated from each other by 
thin sheets of asbestos paper, to prevent loss of energy 
and heating due to eddy currents, and are kept in place 
by clamping-plates and end-nuts. The conductors on the 
armature, which carry the current, are made up of copper 
wires, twisted together, and pressed to a rectangular 
section. They are insulated by a covering of varnished 
tape. Usually two lengths of bars are used. They are 
placed around the periphery of the armature, longitudi- 
nally, long and short bars alternating, their ends overhang- 
ing the core. All the ends at one end of the armature 
project the jame distance. Projections are fitted into the 



AUXILIARY MACHINERY AND FITTINGS 263 

core at intervals, which drive the conductor-bars. These 
projections are insulated by mica slips. The bars are 
kept in place by bands of steel or bronze binding wire, 
tightly wound on and soldered. Mica strips are placed 
under the bands to prevent injury to the insulation of the 
bars. Each bar is connected at each end by bent copper 
strips to another bar almost diametrically opposite to it, 
so that the whole of the bars and end-connections form 
one closed circuit. The projecting end of each long bar 
is also connected to the nearest commutator segment, the 
number of segments being equal to the number of long 




Fig. 168. Armature 

bars. Two or more pairs of brushes bear on the commu- 
tator, to collect the current, so that any brush may be 
lifted off without interrupting the circuit. 

Ques. 618. — Describe the construction of the field- 
magnet coils. 

Ans. — The field-magnet winding consists of shunt and 
series coils wound on a frame which fits over the 
upper pole-piece. The shunt coils are of small 
wire and high resistance. The ends of the wire 
are connected to the machine terminals. The greater 
part of the magnetism is due to these coils, so that at full 
speed, and when no current is being taken from the 



xi 



264 



QUESTIONS AND ANSWERS 



machine, the electric pressure is normal, that is, 80 or 
100 volts. The series coils are formed of thick copper 
bars and convey the whole current generated. They 
provide additional magnetism, proportional to the current 
flowing in them, and so compensate for the additional 




Fig. 169. Compound Wound Dynamo. 

pressure required to force this current through the 
machine. By the combination of the two sets of coils, the 
pressure is thus independent of the current, so long as the 
speed is constant. In the largest machines there are two 
distinct armature windings laid on side by side, the bars 



^ 



AUXILIARY MACHINERY AND FITTINGS 265 

of the two windings alternating, as also do their respec- 
tive commutator segments. The two windings are con* 
nected in parallel by the brushes, which all have a bearing 
rather wider than the angular width of two commutator 
segments. 

Ques. 619. — In order to obtain satisfactory working, 
what should be done with the commutator occasionally? 

Ans. — It should be turned up, by using a lathe slide- 
rest clamped to the bed-plate and running the engines as 
slowly as possible, and after turning, the commutator 
should be polished. This truing up is necessary in order 
to remove any flat places which are liable to form on the 
segments. The brushes also should be carefully filed to 
fit the commutator curve. The brushes must be care- 
fully set in the holders, with all the tips of each set in a 
line, and the tips of the two sets bearing simultaneously 
on diametrically opposite commutator segments. Gener- 
ally two segments are marked at their ends, with crosses, 
to assist in this adjustment. 

Ques. 620. — How is the electric current carried to the 
different parts of the ship? 

Ans. — By wires of the best copper, thoroughly insu- 
lated and protected from injury by being placed in wooden 
mouldings, or what is still better, iron tubes lined with 
insulating material. The junction boxes have safety 
fuses and connections, arranged in incombustible porce- 
lain or lava blocks. 

Ques. 621. — How are the lamps and motors arranged? 

Ans. — The lamps are attached to substantial supports 
With good protection to the insulation of the wires at their 



r 

266 QUESTIONS AND ANSWERS 

connection. For exposed places extra globes or wire 
screens are provided to prevent breaking of the bulbs. 
The motors are fitted on substantial foundations, with 
switches for handling in convenient positions. The use 
of electric motors is becoming more and more general on 
board vessels as their convenience and freedom from 
waste is known. They can be used for working ven- 
tilating fans, etc., in confined spaces where the heat of 
steam would be objectionable. They also avoid the waste 
due to condensation, radiation and leakage in pipes, 
require very little attention when running and are always 
ready for starting. 

Ques. 622. — What facilities are provided for pumping 
the water out of steam-ships in case of a serious leak? 

Ans. — All steam-ships, including war-vessels, were 
formerly fitted with bilge-pumps worked direct from the 
main engines, and this is still the common practice in the 
mercantile marine. In addition to these pumps, the 
circulating pumps are fitted with bilge as well as sea 
connections, and in some of the larger vessels there are 
four centrifugal pumps which can be used for pumping 
out the bilges, each of these pumps having a capacity of 
at least 1,200 tons of water per hour. 

Ques. 623. — What are some of the requirements of a 
reliable bilge-pumping outfit? 

Ans. — The pump itself should be close to the bilge, 
but the engine for working it should if possible be at a 
high level, so as to be out of the reach of the water in 
case of its rising rapidly. Another point that should be 
kept in view is the provision of large engine-power foi 



AUXILIARY MACHINERY AND FITTINGS 



26? 



working the pumps. The valves for changing the suction 
of the centrifugal pumps from the sea to the bilge are, or 
at least should be, arranged to be worked from the start- 
ing platform, and to enable this to be done quickly in 
case of need, the valves in the sea and bilge-suction pipes 



r \ 



7~~T 





I , I 



3 t 



i 





\Q_©_©/ 



2ZE 



Fig. 170. Fire and Bilge Pumps. 

are often coupled together so that they may be worked 
by a single lever. 

Ques. 624. — Describe the type of fire and bilge-pump- 
ing engines that are used to a large extent in the English 
navy. 



^ 



268 QUESTIONS AND ANSWERS 

Ans. — Each pumping engine consists of two double- 
acting pumps and two steam-cylinders, fitted with 
slide-valves, having very little lap, to insure the engines 
starting readily from any position of the cranks, economy 
in the use of steam being in these cases a minor considera- 
tion. In the large battle-ships and cruisers there are four 
[of these pumps, two in each engine-room, each one of the 
four having a capacity of 80 to 120 tons of water per 
hour. The pumps are large enough to remove these 
quantities of water at a speed not exceeding 60 revolu- 
tions per minute, with a steam-pressure of two-thirds 
the maximum boiler-pressure, and they form a means of 
pumping water out of the ship, auxiliary to the main 
circulating pumps. They can be used for either fire ser- 
vice or for clearing the bilges of water. 

Ques. 625. — Describe Friedmann's bilge-ejector. 

Ans. — This apparatus is a modification of Giffard's 
injector, the number of nozzles being increased so as to 
give the steam several suction orifices instead of one. 
The steam is conducted to a tuyere about one-half the 
diameter of the steam-pipe, and then passes successively 
through a series of intermediate tuyeres, through which 
the water is drawn from the hold and expelled from the 
ship through the discharge. The device occupies little 
space and has considerable capacity, but its consumption 
of steam is large. 

Ques. 326. — Describe the suction and discharge 
arrangements of fire and bilge pumps. 

Ans. — They are fitted with separate suction-pipes 
leading to the following parts of the vessel: Forward 



n. 



AUXILIARY MACHINERY AND FITTINGS 



269 



and after ends of engine-room, with a continuation to 
the screw tunnel from the latter, main engine save-all, 
each boiler compartment, the main suction-pipe, salvage 
system of the vessel and to the sea. The valve-boxes 
and pipes are so arranged that each pump can draw from 
any of these parts. The pumps deliver water either over- 
board direct, to the engine-room or to the fire-main, a 
large air-vessel being fitted in connection with the latter. 




J)/SCHAROe TO 

enginc room*' r"n 



D ,0*0*9 CCNHCCTIOM 
T=»i /BtTWeCJ?, SVCTtON BOXCS 




\ MAIM SUCT/OAt pUf 



SUCTION r/tOM SCA. 



S£A 
[VALV£ , 



sue TIOW FACM SSA. 



Fig. 171. Suction and Discharge Arrangements oe Fire and Bilge Pumps. 

A A A A, pumps; B B, directing valve-boxes; C C, shut-off valves from 
the sea, and bilge directing valve-box respectively; D D, directing valves for 
discharge, either to fire main, overboard or to engine-room. 

Ques. 627. — How is the fire-main arranged? 

Ans. — The fire-main is a pipe extending fore and aft 
in the ship, with branches leading to different parts as 
required. Delivery-valves, with screwed nozzles for hose- 
connections, i are located at various points in the fire-main. 
Non-return valves are fitted at the junction of delivery- 
pipes from the pumping engines. 



CHAPTER IX 

THE INDICATOR — PRINCIPLES OF THE INDICATOR 

Ques. 628. — By whom was the indicator invented and 
first applied to the steam-engine? 




Fig. 172. Sectional View Crosby Indicator. 

Ans. — The indicator was invented and first applied to 
the steam-engine by James Watt, whose restless genius 

270 



k> 



THE INDICATOR PRINCIPLES OF INDICATOR 



271 



was not satisfied with a mere outside view of his engine 
as it was running, but he desired to know more about the 
action of the steam in the cylinder, its pressure at differ- 
ent portions of the stroke, the laws governing its expan- 
sion after being cut off, etc. Watt's indicator, although 
crude in its design and construction, contained embodied 
within it all of the principles of the modern instrument. 

Ques. 629. — What are the principles governing the 
action of the indicator? 

Ans. — First, the pressure of the 
Steam in the; engine-cylinder throughout 
an entire revolution, against a small pis- 
ton in the cylinder of the indicator, which 
in turn is controlled or resisted in its 
movement by a spring of known tension, 
so as to confine the stroke of the indica- 
tor piston within a certain small limit. 
Second, the stroke of the indicator pis- 
ton is communicated by a multiplying 
mechanism of levers and parallel motion 
to a pencil moving in a vertical straight 
line, the distance through which the pencil moves being 
governed by the pressure in the engine-cylinder and the 
tension of the spring. Third, by the intervention of a re- 
ducing mechanism and a strong cord, the motion of the pis- 
ton of the engine throughout an entire revolution is com- 
municated to a small drum attached to and forming a part 
of the indicator. The movement of the drum is rotative 
and in a direction at right angles to the movement of the 
pencil. The forward stroke of the engine-piston causes 




Fig. 173. 

Crosby Indicator 

Spring. 



* 



272 



QUESTIONS AND ANSWERS 



the drum to rotate through part of a revolution and at 
the same time a clock-spring connected within the drum 
is wound up. On the return stroke the motion of the 
drum is reversed, and the tension of the spring returns 
the drum to its original position and also keeps the cord 
taut. 

Ques. 630. — Describe in general terms the construc- 
tion of an indicator. 

Ans. — An indicator con- 
sists of a small cylinder, 
open to the atmosphere at 
the top and having its bot- 
tom end connected by suit- 
1 able pipes and stop-cocks 
to both ends of the engine- 
cylinder in such a manner 
that the steam-pressure in 
either end may be caused 
to act upon the indicator 
FlG piston, as required. The 

S.CTIONAI, View Thom'pson Indicator. cyHnder q£ ^ indicator 

stands vertical, and is of a known area, usually about one 
square inch. It contains a piston, upon which the steam 
acts only on the under side, the top of the cylinder being 
open to the atmosphere. The length of stroke of this 
piston is regulated and controlled by a steel spiral spring 
of known tension, which acts in resistance to the pressure 
of the steam. When the cock connecting the cylinders of 
the engine and indicator is closed, both ends of the indi- 
cator cylinder are open to atmospheric pressure, and the 




^ 



THE INDICATOR PRINCIPLES OF INDICATOR 273 

pencil, which is connected to the piston by a system oj 
levers, stands at its neutral position. 

Ques. 631. — Describe the construction and action \d 
the spiral spring in connection with the indicator pistou. 

Ans. — These springs are made of different tensions in 
order to be suitable to different steam-pressures and 
speeds, and are numbered 20, 40, 60, etc., the number 
meaning that a pressure per square inch 
in the engine-cylinder corresponding to 
the number on the spring will cause a 
vertical movement of the pencil through 
a distance of one inch. Thus, if a No. 
20 spring is used and the pressure in the 
cylinder at the commencement of the 
stroke is 20 pounds per square inch, the 
pencil will be raised one inch, or if the 
pressure is 30 pounds, the pencil will 
travel V/2 inch, and if there is a vacuum 
of 20 inches in the condenser, the pencil 
will drop /. inch below the atmospheric 
line for the reason that 20 inches of vac- 
uum correspond to a pressure of about 
10 pounds less than atmospheric pressure or an absolute 
pressure of about 4 pounds. If a 60 spring is used a 
pressure of 60 pounds in the engine-cylinder will be re- 
quired to raise the pencil one inch, or 90 pounds to raise 
it V/2 inch. 

Ques. 632. — Are these springs placed inside the 
cylinder in all types of indicators? 

Ans. — The Ashcroft Manufacturing Company of New 




Fig. 175. 
Thompson Indica- 
tor Spring. 



. 



274 



QUESTIONS AND ANSWERS 



York, makers of the well-known Tabor indicator, have 
recently introduced a new feature in indicator work by 
connecting the spring on top of the cylinder and in plain 




FlG, 176. Improved Tabor Indicator with Outside Connected Sprinc. 
Ashcroft Mfg. Co., N. Y. 

view of the operator. This arrangement removes the 
spring from the influence of direct contact with the 
steam, and it is subject only to the temperature of the 



THE INDICATOR — PRINCIPLES OF INDICATOR 275 

surrounding atmosphere. It is claimed that as a result 
of this the accuracy of the spring is insured and that no 
allowance need to be made in its manufacture for 
expansion caused by the high temperature to which it is 
subject when located within the cylinder. Another good 
feature of this design is, that the spring can be easily 
removed without disconnecting any one part of the 
instrument in case it is desired to change springs. 

Ques. 633. — What precautions should be observed in 
attaching the indicator to an engine-cylinder? 

Ans. — The main requirements in these connections 
are that the holes shall not be drilled near the bottom of 
the cylinder where water is likely to find its way into 
the pipes, neither should they be in a location where the 
inrush of steam from the ports will strike them directly, 
nor where the edge of the piston is liable to partly cover 
them when at its extreme travel. An engineer before he 
undertakes to indicate an engine should satisfy himself 
that all these requirements are fulfilled. Otherwise he is 
not likely to obtain a true diagram. The cock supplied 
with the indicator is threaded for one-half inch pipe, and 
unless the engine has a very long stroke it is the practice 
to bring the two end connections together at the side or 
top of the cylinder and at or near the middle of its length, 
where they can be connected to a three-way cock. The 
pipe connections should be as short and as free from 
elbows as possible, in order that the steam may strike 
the indicator piston as nearly as possible at the same 
moment that it acts upon the engine-piston. These pipes 
should always be thoroughly blown out and cleaned, by 



276 QUESTIONS AND ANSWERS 

allowing the steam to blow through the open three-way 
cock during several revolutions of the engine before con- 
necting the indicator. If this is not done there is a moral 
certainty that dirt and grit will get into the cylinder of 
the indicator and cause it to work badly and give 
diagrams that are misleading. 

Ques. 634. — How is an indicator diagram or card 
drawn? 



Fig. 177. Three-way Cock. 

Ans. — To the outside of the drum a piece of blank 
paper of suitable size is attached and held in place by two 
clips. Upon this paper the pencil in its motion up and 
down traces a complete diagram of the pressures and 
other interesting events transpiring within the engine- 
cylinder during the revolution of the engine. In fact, the 
diagram traced upon the paper is the compound result of 
two concurrent movements. First, that of the pencil 
caused by the pressure of the steam against the indicator 



THE INDICATOR PRINCIPLES OF INDICATOR 277 

piston; second, that of the paper drum caused by, and 
coincident with the motion of the engine-piston. 

Ques. 635. — How is the atmospheric line drawn? 

Ans. — By holding the pencil to the paper, and causing 
the drum to be rotated, when the pencil stands at its neutral 
position, that is with the steam shut off from the indica- 
tor cylinder. 

Ques. 636. — What is meant by the term atmospheric 
line? 

Ans. — The atmospheric line is a horizontal line drawn 
on the diagram and means the line of atmospheric pres- 
sure. If the engine is a non-condensing engine the pencil 
in tracing the diagram will, or at least should not fall 
below the atmospheric line at any point, but will on the 
return stroke trace a line called the line of back pressure 
at a distance more or less above the atmospheric line and 
very nearly parallel with it. If the engine is a condensing 
engine the pencil will drop below the atmospheric line 
while tracing the line of back pressure on the diagram, 
and the distance this line is below the atmospheric line 
will depend upon the number of inches of vacuum in the 
condenser. 

Ques. 637. — Is the atmospheric line a necessary part 
of an indicator diagram? 

Ans. — The atmospheric line is a very important factor 
in the study of the diagram. 

Ques. 638. — How are the dimensions of the diagram 
regulated? 

Ans. — It is a convenient practice to select a spring 
numbered one-half of the boiler-pressure as, for instance, 



A 



278 



QUESTIONS AND ANSWERS 



suppose gauge-pressure or boiler-pressure is 200 pounds 
per square inch, then a 100 spring would give a diagram 
2 inches in height, which is a convenient height. As to 
the length of the diagram, this is regulated by adjustment 




Fig. 178. Crosby Reducing Wheel Attached to Indicator. 



of the cord in its travel, by means of the reducing wheeL 
Any length of diagram up to four inches may be obtained, 
but two and a half to three inches is a very good length 
for analysis. 

Ques. 639. — How is the motion of the crosshead of 



THE INDICATOR PRINCIPLES OF INDICATOR 



279 



the engine reduced and utilized for rotating the drum of 
the indicator? 

Ans. — There are various mechanisms used for this 
purpose. Probably the only practically universal 




mechanism ior reducing the motion of the crosshead is 
the reducing wheel, a device in which, by the employment 
of gears and pulleys of different diameters, the motion is 
reduced to within the compass of the drum, and the 



280 



QUESTIONS AND ANSWERS 



device is applicable to almost any make of engine] 
whether of high or low speed. Some makers of indicator; 
attach the reducing wheel directly to the indicator, thui 
producing a neat and very convenient arrangement, 

Ques. 640. — Describe the construction of the woodei 
pendulum for reducing the motion. 

Ans. — It consists of a flat strip of pine or other lightl 




Wooden Pendulum, Reducing Motion. 

wood of a length not less than one and a half times the 
stroke of the engine, and if made longer it will be better. 
It should be from Z A to 7 /s inch thick and have an average 
width of about 4 inches. If the engine to be indicated is 
horizontal the bar or pendulum is to be pivoted at a fixed 
point directly above and in line with the side of the cross- 
head, as that is generally the mo^t convenient point of 
attachment. The pivot can be fixed to a permanent 



THE INDICATOR PRINCIPLES OF INDICATOR 281 

standard bolted to the frame of the engine or it may be 
secured to the ceiling of the room or even to a post 
fastened to the floor. If the engine is vertical the bar 
can be pivoted to the wall of the room or a strong post 
firmly secured to the floor. The connection with the 
crosshead is best accomplished by means of a short bar or 
link. A convenient length for this bar is one-half the 
stroke of the engine. 

Ques. 641. — When the short bar is one-half the 
length of the stroke, how is the correct point for the loca- 
tion of the pivot for the pendulum found? 

Ans. — Place the engine on the center with the cross- 
head at the end of the stroke towards the crank. Then 
having previously bored a hole for the pivot in one end 
of the pendulum bar and in the other end a hole for con- 
necting with the link, susoend the pendulum by a 
temporary pin, as a large wood screw, directly above and 
in line with the stud or bolt hole which has previously 
been tapped into the crosshead at any convenient point. 
The pendulum should be temporarily suspended at such 
a height that when it hangs perpendicular the hole in its 
lower end will line up accurately with the hole or stud in 
the crosshead. Now swing the pendulum in either direc- 
tion a distance equal to the length of the link (one-half 
the stroke of the engine) from the crosshead connection 
and note the distance that the bottom hole is above a 
(straight edge laid horizontal and in line with the center 
of the stud in the crosshead. This will give the total 
vibration of the free end of the link from a line parallel 
with the line of the engine and the permanent location of 



282 QUESTIONS AND ANSWERS 

the pivot should be one-half of this distance below th< 
temporary point of suspension. This will allow the link 
to vibrate equally above and below the center of its con 
nection with the crosshead. 

Ques. 642. — How is the correct point of attachment 
of the cord to the pendulum found? 

Ans. — The cord can be attached to the pendulum at 
point near the pivot, which will give the desired length ol 
diagram. This point can be determined by multiplyinj 
the length of the pendulum by the desired length of dia- 
gram and dividing the product by the stroke. Foi 
convenience these terms should be expressed in inches. 
Thus, assume stroke of engine to be 48 inches, length of 
pendulum V/2 times length of stroke = 72 inches. 
Desired length of diagram 3 inches. Then 72X3-^48 = 4.5 
inches, which is the distance from center of pivot to point 
of connection for the cord. This can be either a smal 
hole bored through the pendulum or a wood screw to 
which the cord can be attached. From this point the 
cord should be led over a guide pulley located at such 
height that when the pendulum is vertical the cord wil 
leave it at right angles. After leaving the guide pulley 
the cord can be carried at any angle desired. 

Ques. 643. — How shoulu the indicator be cared for? 

Ans. — The indicator should be cleaned and oiled 
both before and after using. The best material for 
wiping it is a clean piece of old soft muslin of fine texture, 
as there is not so much liability of lint sticking to or 
getting into the small joints. Use good clock oil for the 
ioints and springs, and before taking diagrams it is a good 



THE INDICATOR PRINCIPLES OF INDICATOR 283 

practice to rub a small portion of cylinder oil on the 
piston and the inside of the cylinder, but when about to 
put the instrument away these should be oiled with clock 
oil also. 

Ques. 644. — How may the cord be adjusted to proper 
length? 

Ans. — None but the best cord should be used for con- 
necting the paper drum with the reducing motion, as a 
cord that is liable to stretch will cause trouble. After 
the indicator has been screwed on to the cock connecting 
with the pipe, the cord must be adjusted to the proper 
ength before hooking it on to the drum. This must be 
lone while the engine is running, by taking hold of the 
oop on the cord connected with the reducing motion 
with one hand, and with the other hand grasp the hook 
)n the short cord attached to the drum, then by holding 
:he two ends near each other during a revolution or two 
t will be seen whether the long cord needs to be shortened 
r lengthened. 

Ques. 645. — What precautions are necessary in regard 
o the paper and pencil in order to secure a truthful 
liagram? 

Ans. — Care should be exercised in placing the paper 
>n the drum to see that it is stretched tight and firmly 
leld by the clips. The pencil point having been first 
harpened by rubbing it on a piece of fine emery cloth or 
and paper should be adjusted by means of the pencil 
|top with which all indicators should be provided, so that 
will have just sufficient bearing against the paper to 
lake a fine, plain mark. If the pencil bears too hard on 



284 QUESTIONS AND ANSWERS 

the paper it will cause unnecessary friction and the di; 
gram will be distorted. The best method of ascertain^ 
this fact and also whether the travel of the drum 
equally divided between the stops, is to place a blank die 
gram on the drum, connect the cord and while the engir 
makes a revolution hold the pencil against the pape 
Then unhook the cord, remove the paper and if the trav 
of the drum is not divided correctly it can be changed. 

Ques. 646. — Describe the process of taking an indica 
tor diagram. 

Ans. — Place a fresh blank on the drum, being carefi 
to keep the pencil out of contact with it, connect the con 
open the cock admitting steam to the indicator and aft< 
the pencil has made a few strokes to allow the cylinder t 
become warmed up, then gently swing it around to th 
paper drum and hold in there while the engine makgs 
complete revolution. Then move the pencil clear of th 
paper, close the cock and unhook the cord. Now trac 
the atmospheric line by holding the pencil against th' 
paper while the drum is revolved by hand. This metho< 
of tracing the atmospheric line is preferable to that o 
tracing it immediately after closing the cock and whili 
the drum is still being moved by the engine, for the reasoi 
that there is not so much liability of getting the atmos« 
pheric line too high owing to the presence of a sligh 
pressure of steam remaining under the indicator pistol 
for a second or two just after closing the cock; also th< 
line drawn by hand will be longer than one drawn whil< 
the drum is moved by the motion of the engine and wi 
therefore be more readily distinguished from the line oi 
back pressure. 



THE INDICATOR— PRINCIPLES US? INDICATOR 3§§ 

Ques. 647. — What other details should be observed in 
the taking of indicator diagrams? 

Ans. — As soon as the diagrams are taken the following 
data should be noted upon them: The end of the cylinder, 
whether head or crank; boiler-pressure, and time when 
taken. Other data can be added afterwards. 

Ques. 648. — What needed changes in the cut-off of a 
Corliss engine, as shown by a diagram, may be made while 
the engine is running? 

Ans. — If the engine is an automatic cut-off of the 
Corliss type and the point of cut-off on one end does not 
coincide with the other, the difference can generally be 
adjusted while the engine is running by changing the 
length of the rods extending from the governor to the 
tripping device. These rods are, or should be fitted with 
right and left threads on the ends for this purpose. Any 
changes in the valves, such as giving them more lead, 
compression, etc., and which necessitates changing the 
length of the reach rods connecting them with the wrist 
plate, will have to be made while the engine is stopped, 
although with slow-speed engines and the exercise of 
caution it is possible to make alterations in these rods 
while the engine is running. 

Ques. 649. — What important details will a truthful 
indicator diagram show? 

Ans. — First, the pressure of the steam against the 
piston of the engine at any point in the stroke during a 
complete revolution; second, diagrams from a condensing 
engine show the amount of vacuum that is being maint- 
ained in the condenser, measured from the line of perfect 



286 QUESTIONS AND ANSWERS 

vacuum; third, the point of cut-off is clearly shown, als< 
the point in the return stroke at which compressioi 
begins; fourth, the expansion curve, and how near i 
approaches the theoretical expansion curve; fifth, an] 
fault in the setting of the valves is clearly shown 01 
the diagram; sixth, diagrams taken from the differen 
cylinders of a compound or stage expansion engine ma; 
be combined in such a manner as to show whether or no 
the cylinders are properly proportioned, and whether th< 
steam is being distributed correctly. 

Ques. 650. — What is absolute pressure? 

Ans. — Pressure reckoned from a perfect vacuum. It 
equals the boiler-pressure plus the atmospheric pres 
sure. 

Ques. 651 — What is boiler-pressure or gauge-pres- 
sure? 

Ans. — Pressure above the atmospheric pressure as 
shown by the steam gauge. 

Ques. 652. — What is initial pressure? 

Ans. — Pressure in the cylinder at the beginning of the 
stroke. 

Ques. 653. — What is meant by terminal pressure (T. 

p.)? 

Ans. — The pressure that would exist in the cylinder 
at the end of the stroke provided the exhaust valve did 
not open until the stroke was entirely completed. It 
may be graphically illustrated on the diagram by extend- 
ing the expansion curve by hand to the end of the stroke, 
It is found theoretically by dividing the pressure at point 
of cut-off by the ratio of expansion. Thus, absolute 



THE INDICATOR — PRINCIPLES OF INDICATOR 287 

pressure at cut-off =100 pounds, ratio of expansion=5; 
then 100-^-5^=20 pounds, absolute terminal pressure. 
Ques. 654. — What is mean effective pressure (M. E. 

p.)? 

Ans. — The average pressure acting upon the piston 
througnout the stroke minus the back pressure. 

Ques. 655. — What is back pressure? 

Ans. — Pressure which tends to retard the forward 
stroke of the piston. Indicated on the diagram from a 
non-condensing engine by the height of the back pressure 
line above the atmospheric line. In a condensing engine 
the degree of back pressure is shown by the height of the 
back pressure line above an imaginary line representing the 
pressure in the condenser corresponding to the degree 
of vacuum in inches, as shown by the vacuum gauge. 

Ques. 656. — What is total or absolute back pressure? 

Ans. — Total or absolute back pressure, in either a 
ondensing or non-condensing engine, is that indicated 
on the diagram by the height of the line of back pressure 
above the line of perfect vacuum. 

Ques. 657. — How is the line of perfect vacuum drawn 
Dn an indicator diagram? 

Ans. — The line of perfect vacuum is drawn parallel 
with the atmospheric line and at a distance below the 
atter, representing 14.7 pounds, as measured by the scale 
:orresponding to the spring that was used in taking the 
liagram. Different scales are supplied for the different 
prings used. 

Ques. 658. — What is meant by ratio of expansion? 

Ans. — The Drooortion that the volume of steam in the 



288 QUESTIONS ANEf ANSWERS 

cylinder at point of release bears to the volume at cut-off. 
Thus, if the point of cut-off is at one-fifth of the stroke, 
and release does not take place until the end of the stroke, 
the ratio of expansion, or in other words, the number oi 
expansions, is 5. When the T. P. is known the ratio oJ 
expansion may be found by dividing the initial pressure 
by the T. P. 

Ques. 659. — What is rteart by wire drawing? 

Ans. — When through insufficiency of valve opening, 
contracted ports or throttling governor, the steam is 
prevented from following up the piston at full initial 
pressure until the point of cut-off is reached, it is said to 
be wire drawn. It is indicated on the diagram by a 
gradual inclination downwards of the steam line from 
the admission line to the point of cut-off. Too small a 
steam pipe from boiler to engine will also cause wire 
drawing and fall of pressure. 

Ques. 660. — What is condenser pressure? 

Ans. — Condenser pressure may be defined as the pres- 
sure existing in the condenser of an engine, caused by 
the lack of a perfect vacuum. As, for instance, with a 
vacuum of 25 inches there will still remain the pressure 
due to the 5 inches which is lacking. This will be about 
2.5 pounds. 

Ques. 661. — What 'is absolute zero? 

Ans. — Absolute zero has been fixed by calcula- 
tion at 461.2 degrees below the zero of the Fahrenheit 
scale. 

Ques. 662. — What is piston displacement? 

Ans. — The space or volume swept through by the 



THE INDICATOR — PRINCIPLES OF INDICATOR 289 

piston in a single stroke. Found by multiplying the 
area of piston by length of stroke. 

Ques. 663. — What is piston clearance? 
Ans. — The distance between the piston and cylinder 
head when the piston is at the end of the stroke, 

Ques. 664. — What is steam clearance, ordinarily 
termed clearance? 

Ans. — The space between the piston at the end of the 
stroke and the valve face. It is reckoned in per cent 
of the total piston displacement. 

Ques. 665. — What is the meaning of the expression 
horse-power as applied to a steam-engine? 

Ans. — 33,000 pounds raised one foot high in one 
minute of time. 

Ques. 666. — What is indicated horse-power (I. H. P.)? 
Ans. — The horse-power as shown by the indicator 
diagram. It is found as follows: Area of piston in 
square inchesXM. E. P. X piston speed in feet-^33,000. 
Ques. 667.— What is meant by the term piston speed? 
Ans. — The distance in feet traveled by the piston in 
one minute. It is the product of twice the length of 
stroke expressed in feet multiplied by the number of 
revolutions per minute. 

Ques. 668.— What is net horse-power? 
Ans. — I. H. P. minus the friction of the engine. 
Ques. 669. — What is compression? 
Ans. — The action of the piston as it nears the end of 
he stroke, in reducing the volume and raising the pres- 
ure of the steam retained in the cylinder ahead of the 
rfston by the closing of the exhaust valve. 



290 QUESTIONS AND ANSWERS 

Ques. 670. — What is Boyle's law of expanding gases? 

Ans. — "The pressure of a gas at a constant tempera- 
ture varies inversely as the space it occupies." Thus, 
if a given volume of gas is confined at a pressure of 
50 pounds per square inch and it is allowed to expand to 
twice its volume, the pressure will fall to 25 pounds per 
square inch. 

Ques. 671. — What is an adiabatic curve? 

Ans. — A curve representing the expansion of a gas 
which loses no heat while expanding. Sometimes called 
the curve of no transmission. 

Ques. 672. — What is an isothermal curve? 

Ans. — A curve representing the expansion of a gas 
having a constant temperature but partially influenced 
by moisture, causing a variation in pressure according 
to the degree of moisture or saturation. It is also called 
the theoretical expansion curve. 

Ques. 673. — What is the expansion curve? 

Ans. — The curve traced upon the diagram by the 
indicator pencil showing the actual expansion of the steam 
in the cylinder. 

Ques. 674. — What is power? 

Ans. — The rate of doing work, or the number of foot 
pounds exerted in a given time. 

Ques. 675. — What is the unit of work? 

Ans. — The foot pound, or the raising of one pound 
weight one foot high. 

Ques. 676. — Define the first law of motion. 

Ans. — All bodies continue either in a state of rest or 
of rjiifarm motion in a straight line, except in so far as 



THE INDICATOR— PRINCIPLES OF INDICATOR 291 

they may be compelled by impressed forces to change that 
state. 

Ques. 677.— What is work? 

Ans.— Mechanical force or pressure can not be con- 
sidered as work unless it is exerted upon a body and 
causes that body to move through space. The product 
of the pressure multiplied by the distance passed through 
and the time thus occupied is work. 

Ques. 678.— What is momentum? 

Ans.— Force possessed by bodies in motion, or the 
product of mass and density. 

Ques. 679.— What is the meaning of the word dynam- 
ics? 

Ans.— The science of moving powers or of matter in 
motion, or of the motion of bodies that mutually act upon 
each other. 

Ques. 680.— What is force? 

Ans.— That which alters the motion of a body or puts 
in motion a body that was at rest. 

Ques. 681.— What is the maximum theoretical duty 
of steam? 

Ans.— The maximum theoretical duty of steam is the 
product of the mechanical equivalent of heat, viz., 778 
foot pounds multiplied by the total heat units 'in a 
pound of steam. Thus, in one pound of steam at 212 
degrees reckoned from 32 degrees the total heat equals 
1,146.6 heat units. Then 778X1,146.6 = 892,054.8 foot 
oounds=maximum duty. 

Ques. 682.— What is steam efficiency? 

Ans.— Steam efficiency mav be expressed as follows: 



292 QUESTIONS AND ANSWERS 

H,eat converted into useful work . 

Heat expended and maxunum efficiency 

can only be attained by using steam at as high an initial 
pressure as is consistent with safety, and at as large a 
ratio of expansion as possible. 

Ques. 683. — What is meant by the term efficiency o{ 
the plant as a whole? 

Ans. — Efficiency of the plant as a whole includes 
boiler and engine efficiency, and is to be figured upon the 
- Heat converted into useful work 
Calorific or heat value of fuel 

Ques. 684. — What is the horse-power constant of an 
engine? 

Ans. — The horse-power constant of an engine is founc 
by multiplying the area of the piston in square inches b] 
the speed of the piston in feet per minute and dividing 
the product by 33,000. It is the power the engine woul<* 
develop with one pound mean effective pressure. To fin(f 
the horse-power of the engine, multiply the M. E. P. ol 
the diagram by this constant. 

Ques. 685. — What is meant by the expression steam 
consumption per horse-power per hour? 

Ans. — The weight in pounds of steam exhausted info 
the atmosphere or into the condenser in one hour divided 
by the horse-power developed. It is determined from the 
diagram by selecting a point in the expansion curve just 
previous to the opening of the exhaust-valve and 
measuring the absolute pressure at that point. Then the 
pfston displacement up to the point selected, plus 
the clearance space, expressed in cubic feet, will 



THE INDICATOR — PRINCIPLES OF INDICATOR 293 

give the volume of steam in the cylinder, which multiplied 
by the weight per cubic foot of steam at the pressure 
as measured will give the weight of steam consumed during 
one stroke. From this should be deducted the steam 
saved by compression as shown by the diagram, in order 
jto get a true measure of the economy of the engine. 
Having thus determined the weight of steam consumed 
for one stroke, multiply it by twice the number of 
strokes per minute and by 60, which will give the total 
weight consumed per hour. This divided by the horse- 
power will give the rate per horse-power per hour. 

Ques. 686. — What is cylinder condensation and 
reevaporation? 

Ans. — When the exhaust-valve opens to permit the 
exit of the steam there is a perceptible cooling of the 
walls of the cylinder, especially in condensing engines 
when a high vacuum is maintained. This results in 
more or less condensation of the live steam admitted by 
the opening of the steam- valve; but if the exhaust- 
valve is caused to close at the proper time so 
as to retain a portion of the steam to be compressed by 
the piston on the return stroke, a considerable poition 
of the water caused by condensation will be reevaporated 
into steam by the heat and consequent rise in pressure 
caused by compression. 

Ques. 687. — What are ordinates, as applied to indi- 
cator diagrams? 

Ans. — Parallel lines drawn at equal distances apart 
across the face of the diagram and perpendicular to the 
atmospheric line. They serve as a guide to facilitate the 



294 



QUESTIONS AND ANSWERS 



■measurement of the average forward pressure through- 
out the stroke, or the pressure at any point of the stroke 
if desired* 

Ques. 688. — What is a throttling governor? 

Ans. — A governor that is used to regulate the speed 
of engines having a fixed cut-off. The governor controls 
the position of a valve in the steam-pipe, opening or clos« 



*W 







Fig. 180. Illustrating the Process of Obtaining the Mean Eeeectiv* 
Pressure by Means oe Ordinates. 

ing it according as the engine needs more or less steam in 
order to maintain a regular speed. 

Ques. 689. — What is an automatic or variable cut- 
off engine? 

AnSc — In engines of this type the full boiler pressure 
is constantly in the valve chest and the speed of the 
engine is regulated by the governor controlling the point 
of cut-off, causing it to take place earlier or later 
according as the load on the engine is lighter or heavier. 



THE INDICATOR PRINCIPLES OF INDICATOR 295 

Ques. 690.— What is a fixed cut-off? 

Ans. — This term is applied to engines in which the 
point of cut-off remains the same regardless of the load, 
the speed being regulated by a throttling governor. 

Ques. 691. — What is an adjustable cut-off? 

Ans. — One in which the point of cut-off may be regu- 
lated or adjusted by hand by means of a hand wheel and 
screw attached to the valve stem, the supply of steam 
being regulated by a throttling governor. 

Ques. 692. — What is an isochronal or shaft governor? 




Fig. 181. Indicator Diagram Taken from a Condensing Engine. 

A, atmospheric line. V, line of perfect vacuum. B to D, admission line. 
D to E, steam line. E, point of cut-off. E to F, expansion line. F to G, ex- 
haust. G to C, line of back pressure; and from C to B shows compression. 



Ans. — This device in which the centrifugal and cen- 
tripetal forces are utilized, as in the fly-ball governor, is 
generally applied to automatic cut-off engines having 
reciprocating or slide valves. It is attached to the crank 
shaft and its function is to change the position of the 
eccentric, which is free to move across the shaft within 
certain prescribed limits, but is at the same time attached 
to the governor. The angular advance of the eccentric 
is thus increased or diminished; in fact is entirely under 



296 



QUESTIONS AND ANSWERS 



the control of the governor, and cut-off occurs earlier of 
later according to the demands of the load on the 
engine. 

Ques. 693. — If the valves of an engine are properly 
adjusted and the distribution of the steam is approxi- 
mately correct, what particular features should character- 
ize an indicator diagram taken from it? 

Ans. — First, the admission line at the beginning of the 
stroke should be perpendicular to the atmospheric line; 
second, the steam line, as it is called, extending from the 
beginning of the stroke to the point of cut-off, should be 




Fig. 182. Diagram Showing Insufficient Lead. 



parallel with the atmospheric line; third, the point of 
cut-off should be sharply defined; fourth, the expansion 
curve, extending from the point of cut-off to the point of 
release, should conform as near as possible with the 
isothermal curve, which can easily be applied to any dia- 
gram; fifth, the exhaust line, extending from point of 
release to that point in the return stroke where compres- 
sion begins, should be parallel with and practically coin- 
cident with the atmospheric line, if the engine is 
non-condensing:, or if the engine be a condensing engine, 



THE INDICATOR PRINCIPLES OF INDICATOR 29? 

this line should approach within a few pounds of the line 
of perfect vacuum. 

Ques. 694. — If the admission line inclines inward 
from the perpendicular, what defect in the valve setting 
is indicated? 

Ans. — Insufficient lead. 

Ques. 695.— How is wire drawing of the steam 
detected by the indicator diagram? 

Ans. — By the downward inclination of the steam line 
toward the point of cut-off. 




Fig. 183. Diagram Showing Effects of Wire Drawing the Steam. 



Ques. 696. — What is a very necessary factor in the 
calculation of the horse-power of an engine as shown by 
a diagram taken from it? 

Ans. — The mean effective pressure. 

Ques. 697.— How is the M. E. P. of a diagram ascer- 
tained? 

Ans. — There are two methods commonly used. First, 
by means of ordinates, and secondly, by the use of the 
planimeter. 



298 



QUESTIONS AND ANSWERS 



Ques. 698. — Describe the method of finding the M 
E. P. by ordinates. 

Ans. — The process consists in drawing any convenienl 
number of vertical lines perpendicular to the atmospheric 
line across the face of the diagram, spacing them equally 
with the exception of the two end spaces, which shoul< 
be one-half the width of the others, for the reason tha 
the ordinates stand for the centers of equal spaces. This 
is an important matter, and should be thoroughly under 



Cr/fn/(£/jil 




SS 

3 

'9 

to./ 
8 

7 






2 7 2 'Jr/6.Jju>/7& 



'fit* 



Fig. 184. Finding M. E. P. 



Stood, because if the spaces are all made of equal width, 
and measurements are taken on the ordinates, the result! 
will be incorrect, especially in the case of high initial pres- 
sure and early cut-off, following which the steam undergoes 
great changes. If the spaces are all made equal, the meas- 
urements will require to be taken in the middle of them, and 
errors are liable to occur, whereas if spaced as before 
described, the measurements can be made on the ordinates, 
which is much more convenient and will insure correct 
results. Any number of ordinates can be drawn, but ten 



THE INDICATOR PRINCIPLES OF INDICATOR 



299 



is the most convenient and is amply sufficient, except in 
case the diagram is excessively long. 

Ques. 699. — Having succeeded in drawing the ordi- 
nates across the face of the diagram, what is the next step? 

Ans. — The pressure represented by each line is meas- 
ured from the exhaust line to the steam line, and so on, 




FlG. 185. Pl^ANIMETER. 

along the expansion curve throughout the length of the 
diagram, using for this purpose the scale adapted to the 
fpring used, and having thus obtained measurements on 
each line, add all together and divide the sum total by 
the number of lines, which will give the mean forward 
pressure. To obtain the mean effective pressure, deduct 
the back pressure, which is represented by the distance 



300 



QUESTIONS AND ANSWERS 



of, the exhaust line above the atmospheric line in a non- 
condensing engine, and in a condensing engine the back 
pressure is measured from the line of perfect vacuum. 




Fig. 186. Coffin Averager or Planimeter. 



Ques. 700. — What is a planimeter? 

^ rs# — The planimeter is an instrument which will 



THE INDICATOR PRINCIPLES OF INDICATOR 301 

accurately measure the area of any plane surface, no 
matter how irregular the outline or boundary line is. 

Ques. 701. — What is the main requirement in ascer- 
taining the M. E. P. of a diagram? 

Ans. — The prime requisite In making power calcula- 
tions from indicator diagrams is to obtain the average 
height or width of the diagram, supposing it were reduced 
to a plain parallelogram instead of the irregular figure 
which it is. 

Ques. 702. — What advantage is gained by using the 
planimeter in measuring diagrams? 

Ans. — It shows at once the area of the diagram in 
square inches and decimal fractions of a square inch, and 
when the area is thus known it is an easy matter to obtain 
the average height by simply dividing the area in inches 
by the length of the diagram in inches. Having ascer- 
tained the average height of the diagram in inches or 
fractions of an inch the mean or average pressure is 
found by multiplying the height by the scale. Or the 
process may be made still more simple by first multiplying 
the area, as shown by the planimeter in square inches and 
decimals of an inch, by the scale and dividing the product 
by the length of the diagram in inches. The result will 
be the same as before, and troublesome fractions will be 
avoided. 

Ques. 703. — Having obtained the M. E. P., as shown 
by the diagram, how may the horse-power developed by 
the engine be ascertained? 

Ans. — The area of the piston (minus one-half the are* 
of rod) multiplied by the M. E. P., as shown by the dia- 



302 QUESTIONS AND ANSWERS 

gram, and this product multiplied by the number of feet 
traveled by the piston per minute (piston speed) will give 
the number of foot pounds of work done by the engine 
each minute, and if this product be divided by 33,000, 
the quotient will be the indicated horse-power (I. H. P.) 
developed by the engine. 

Ques. 704. — Mention two important factors in calcu- 
lations of steam consumption. 

Ans. — In calculating the steam consumption of an 
engine, two very important factors must not be lost sight 
of, viz., clearance and compression. Especially is this 
the case in regard to clearance when there is little or no 
compression, for the reason that the steam required to fill 
the clearance space at each stroke of the engine is prac- 
tically wasted, and all of it passes into the atmosphere or 
the condenser, as the case may be, without having done 
any useful work except to merely fill the space devoted to 
clearance. On the other hand, if the exhaust valve is 
closed before the piston completes the return stroke, the 
steam then remaining in the cylinder will be compressed 
into the clearance space and can be deducted from the 
total volume which, without compression, would have been 
exhausted at the terminal pressure. 

Ques. 705. — When, owing to light load and early 
cut-off, the expansion curve drops below the line of back 
pressure, how must the area of the diagram be calculated? 

Ans. — The area of the loop below the back pressure 
line must be subtracted from the remainder of the diagram. 
If the planimeter is used, the instrument will make the sub- 
traction automatically, but if the diagram is divided into 



THE INDICATOR PRINCIPLES OF INDICATOR 



303 



parts by ordinates, the pressure shown by the ordinates in 
the lower loop must be subtracted from that shown by 
the loop above the back pressure line in order to ascertain 
the M. E. P. or average pressure. 

Ques. 706. — What is meant by the adiabatic curve? 



7 


,'C 




s 

So 








7* 
7° 

IS 




/ / 






~7 ~T 






/ / 




t>o 




/ / 




5S 




'Jr 




5o 




S> 




HS 




^'^ 












3S 




•f^^^ 




3o 


R 


s-*^*^ 1 


Zi 




J 


A 


V 


V 



Fig. 187. 

The dotted line R C shows what the true adiabatic curve would be on the 
diagram, provided it could be realized. 



Ans. — If it were possible to so protect or insulate the 
cylinder of a steam engine that there would be absolutely 
no transmission of heat either to or from the steam dur- 
ing expansion, a true adiabatic curve or "curve of no 
transmission" might be obtained. The closer the actual 
expansion curve of a diagram conforms to such a curve, 
the higher will be the efficiency of the engine as a 
machine for converting heat into work. 



CHAPTER X 

THE STEAM TURBINE — FUNDAMENTAL PRINCIPLES 

Ques. 707. — What are the basic principles governing 
the action of steam turbines? 

Ans. — There are two fundamental principles upon 
which all steam turbines operate, viz., reaction and 
impulse. In some types of turbines the reaction principle 
alone is utilized, and in others the impulse, while in still 
others, and probably the most successful ones, both 
principles are combined. 

Ques. 708. — In what general direction does the steam 
flow 7 when used in a turbine? 

Ans. — Parallel with the shaft or rotor, and also in a 
screw-like direction around it. This definition does not 
apply, however, to turbines of the purely impulse type, 
like the De Laval, for instance. 

Ques. 709. — What causes the rotor to revolve? 

Ans. — The action of the steam, coming, as it does, 
with tremendous velocity and great force against the 
small buckets or vanes with which the rotor is fitted, 
causes it to revolve, and as there is a continuous current 
of steam passing into the cylinder, the motion is continue 
ous. 

Ques. 710. — What law of turbo-mechanics governs 
the relation of bucket-speed, and fluid or steam speed? _ 

Ans. — For purely impulse-wheels, bucket-speed equals 
one-half of jet-speed. For reaction wheels, bucket-speed 
equals jet-speed. 

804 



STEAM TURBINE — FUNDAMENTAL PRINCIPLES 305 

Ques. 711, — With what velocity would steam of 100 
pounds pressure discharge into a vacuum of 28 inches? 

Ans. — The theoretical velocity would be 3,860 feet per 
second. 

Ques. 712. — What amount of energy would a cubic 
foot of steam under 100 pounds pressure exert if allowed 
to discharge into a vacuum of 28 inches? 

Ans. — 59,900 foot pounds. 

Ques. 713. — Does the steam impinge against the first 
rows or sections of buckets at full pressure? 

Ans. — In turbines of the Parsons type, the initial 
pressure of the steam is practically boiler-pressure, but 
it gradually falls as it p __cs on through the cylinder, 
which becomes larger in diameter as the exhaust end is 
approached. In other types of turbines, the steam is 
admitted to and directed against the blades or buckets, 
through expanding nozzles, and by the time it strikes the 
first stage, or section of moving vanes, the pressure has 
fallen to one-third or less of the original boiler-pressure, 
but the velocity is very great. 

Ques. 714. — In what particular respect does the steam 
turbine appear to possess an advantage over the recipro- 
cating engine, in the use of steam? 

Ans. — The turbine, if designed along correct lines, 
is capable of utilizing in the highest degree one of the 
most valuable properties of steam, viz., velocity. 

Ques. 715. — Give an example of the great increase in 
the amount of work performed by an agent when velocity 
is one of the factors made use of. 

Ans. — Suppose that a man is standing within arm's 



306 QUESTIONS AND ANSWERS 

length of a heavy plate-glass window and that he holds in 
his hand an iron ball weighing 10 pounds. Suppose the 
man should place the ball against the glass and press the 
same there with all the energy he is capable of exerting. 
He would make very little, if any, impression upon the 
glass. But suppose that he should walk away from the 
window a distance of 20 feet, and then exert the same 
amount of energy in throwing the ball against the glass, 
a different result would ensue. The velocity with which 
the ball would impinge against the surface of the glass 
would no doubt ruin the window. Now, notwithstanding 
the fact that weight, energy, and time involved were 
exactly the same in both instances, yet a much larger 
amount of work was performed in the latter case, owing 
to the added force imparted to the ball by the velocity with 
which it impinged against the glass. 

Ques. 716. — Describe the construction and action of 
the De Laval steam turbine. 

Ans. — The De Laval steam turbine is termed by its 
builders a high-speed rotary steam-engine. It has but a 
single wheel, fitted with vanes or buckets of such curva- 
ture as has been found to be best adapted for receiving 
the impulse of the steam-jet. There are no stationary or 
guide-blades, the angular position of the nozzles giving 
direction to the jet. The nozzles are placed at an angle 
of 20 degrees to the plane of motion of the buckets. 
The heat energy in the steam is practically devoted to 
the production of velocity in the expanding or divergent 
nozzle, and the velocity thus attained by the issuing jet 
of steam is about 4,000 feet per second. To attain the 



STEAM TURBINE — FUNDAMENTAL PRINCIPLES 307 

maximum of efficiency, the buckets attached to the 
periphery of the wheel against which this jet impinges 
should have a speed of about 1,900 feet per second, but, 
owing to the difficulty of producing a material for the 
wheel strong enough to withstand the strains induced by 




Fig. 188. The De Lavai, Turbine Wheei, and Nozzles. 

such a high speed, it has been found necessary to limit 
the peripheral speed to 1,200 or 1,300 feet per second. 

Ques. 717. — Describe the action of the steam in its 
passage through the De Laval diverging nozzle. 

Ans.— It is well known that in a correctly designed 
nozzle the adiabatic expansion of the steam from max- 



308 



QUESTIONS AND ANSWERS 



imum to minimum pressure will convert the entire static 
energy of the steam into kinetic. Theoretically this is 
what occurs in the De Laval nozzle. The expanding steam 
acquires great velocity, and the energy of the jet of steair 




issuing from the nozzle is equal to the amount of energy 
that would be developed if an equal volume of steam were 
allowed to adiabatically expand behind the piston of a 
reciprocating engine, a condition, however, which for 
obvious reasons has never yet been attained in practice 



STEAM TURBINE FUNDAMENTAL PRINCIPLES 309 

with the reciprocating engine. But with the divergent 
nozzle the conditions are different. 

Ques. 718. — What is the usual speed of the De Laval 
steam-turbine wheel? 

Ans. — From 10,000 to 30,000 revolutions per minute, 
according to the size of the machine. 

Ques. 719. — How are the difficulties attending such 
high velocities overcome? 

Ans. — By the long, flexible shaft and the ball and 
socket type of bearings, which allow of a slight flexure 
of the shaft in order that the wheel may revolve about its 
center of gravity rather than the geometrical center or 
center of position. All high-speed parts of the machine 
are made of forged nickel steel of great tensile strength. 

Ques. 720. — How is the speed of the De Laval 
turbine -wheel and shaft reduced and transmitted for 
practical purposes? 

Ans. — By a pair of very perfectly cut spiral gears, 
usually made 10 to 1. These gear-wheels are made of 
solid cast steel; or of cast iron with steel rims pressed on. 
The teeth in two rows are set at an angle of 90 degrees to 
each other. This arrangement insures smooth running 
and at the same time checks any tendency of the shaft 
towards end-thrust, thus dispensing with a thrust bearing. 

Ques. 721. — How are the buckets made and fitted to 
the De Laval wheel? 

Ans. — The buckets are drop-forged and made with a 
bulb shank, fitted in slots, that are milled in the rim of 
the wheel. 

Ques. 722. — How many buckets are there? 



310 



QUESTIONS AND ANSWERS 



Ans. — The number of buckets varies according to the 
capacity of the machine. There are about 350 buckets 




U.S g 

__ u a 

1 2 = 

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5 °«» 

C 3 y 

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u_ rt 

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on a 300 norse-power wheel, which is the largest size built 
up to the present time. 



STEAM TURBINE FUNDAMENTAL PRINCIPLES 311 

Ques. 723. — How many of the diverging nozzles are 
fitted to each wheel? 

Ans. — The number of these nozzles depends upon the 
size of the machine, ranging from one to fifteen. They 
are generally fitted with shut-off valves by which one or 
more nozzles can be cut out when the load is light. This 




fc 



Fig. 191. Working Parts of the; De Laval Steam Turbine. 

A. — Turbine shaft. I. — Gear wheel shaft. 

B. — Turbine wheel. J. — Gear wheel bearing, two parts. 

C— Pinion. K.—Oil ring. 

D. — Pinion bearing, two parts. L,. — Gear wheel bearing in position. 

E. — Pinion bearing, two parts. M. — Coupling. 

F. — Wheel bearing with spring. N. — Centrifugal governor. 

G. — Flexible bearing. O. — Gland ad-justing nut. 

H. — Gear wheel. P. — Adjusting nut for flexible bearing 



renders it possible to use steam at boiler-pressure, no 
matter how small the volume required for the load. This 
is a matter of great importance, especially where the load 
varies considerably, as, for instance, there are plants in 
which during certain hours of the day a 300 horse-power 
machine may be taxed to its utmost capacity and during 



312 QUESTIONS AND ANSWERS 

certain other hours the load on the same machine may 
drop to 50 horse-power. In such cases the number of 
nozzles in action may be reduced by closing the shut-off 
valves until the required volume of steam is admitted to 
the wheel. This adds to the economy of the machine. 
After passing through the nozzles, the steam, as elsewhere 
explained, is now completely expanded, and in impinging 
on the buckets its kinetic energy is transferred to the 
turbine wheel. Leaving the buckets, the steam now 
passes into the exhaust-chamber, and out through the 
exhaust-opening, to the condenser or atmosphere, as the 
case may be. 

Ques. 724. — How is the speed of this turbine regu- 
lated? 

Ans. — The governor is of the centrifugal type, 
although differing greatly in detail from the ordinary 
fly-ball governor. It is connected directly to the end of 
the gear-wheel shaft. 

Ques. 725. — Describe the methods of lubricating the 
bearings on the De Laval turbine. 

Ans. — The main shaft and dynamo bearings are ring- 
oiling. The high-speed bearings on the turbine shaft are 
fed by gravity from an oil-reservoir, and the drip-oil is 
collected in the base and may be filtered and used again. 

Ques. 726. — What can be said regarding the steam- 
consumption of this turbine? 

Ans. — Efficiency tests of the De Laval turbine show 
a high economy in steam-consumption, as, for instance, a 
test made by Messrs. Dean and Alain, of Boston, Mass., 
on a 300 horse-power turbine, using saturated steam at 



STEAM TURBINE FUNDAMENTAL PRINCIPLES 



313 



about 200 pounds pressure per square inch and develop- 
ing 333 brake horse-power, showed a steam-consumption 
of 15.17 pounds per brake horse-power, and the same 
machine, when supplied with superheated steam and 
carrying a load of 352 brake horse-power, consumed but 




Fig. 192. The De Lavae Steam Turbine Governor. 

Two weights B are pivoted on knife edges A with hardened pins C, bearingr 
on the spring seat D. E is the governor body fitted in the end of the gear wheeJ 
shaft K and has seats milled for the knife edges A. It is afterwards reduced in 
diameter to pass inside of the weights and its outer end is threaded to receive 
the adjusting nut I, by means of which the tension of the spring, and through 
this the speed of the turbine, is adjusted. When the speed accelerates, the 
weights, affected by centrifugal force, tend to spread apart, and pressing on the 
spring seat at D push the governor pin G to the right, thus actuating the bell 
crank L, and cutting off a part of the flow of steam. 

13.94 pounds per brake horse-power. These results 
compare most favorably with those of the highest type of 
reciprocating engines. 

Ques. 727. — Since the steam is used in but a single 



314 



QUESTIONS AND ANSWERS 



stage or section of buckets in the De Laval turbine, why 
such good economy in the use of steam? 

Ans. — The static energy in the steam as it enters the 
nozzles is converted into kinetic energy by its passage 
through the divergent nozzles, and the result is a greatly 
increased volume of steam leaving the nozzles at a tre- 
mendous velocity, but at a greatly reduced pressure- 
practically exhaust pressure — impinging against the 
buckets of the turbine wheel and thus causing it to 
revolve. 

Table No. 11 
Capacities and Speed of De Laval Turbines 



Horse Power. 


Revolutions 
Turbine Shaft. 


Revolutions 
Main Shaft. 


Approximate 
Weight, 
Pounds. 


5 

10 
20 
75 

110 
225 
300 


30,000 
24,000 
20,000 
16,400 
13,000 
11,060 
10,500 


3,000 
2,400 
2,000 
1,500 
1,200 
900 
900 


330 

650 

1,250 

5,000 

8,000 

15,000 

20,000 



Ques. 728. — Describe in general terms the Curtis 
steam-turbine. 

Ans. — The Curtis turbine is built by the General 
Electric Company at their works in Schenectady, N. Y., 
and Lynn, Mass. The larger sizes are of the vertical 
type, and those of small capacity are horizontal. In the 
vertical type the revolving parts are set upon a vertical 
chaft, the diameter of the shaft corresponding to the size 
of the machine. The shaft is supported by and runs 
upon a step-bearing at the bottom. This step-bearing 



STEAM TURBINE FUNDAMENTAL PRINCIPLES 



315 



consists of two cylindrical cast-iron plates bearing upon 
each other and having a central recess between them into 
which lubricating oil is forced under pressure by a steam 
or electrically driven pump, the oil passing up from 




FiC. 193. 5,000'K. W. Curtis Steam Turbine Direct Connected to 5,000 
K. W. Three-phase Alternating Current Generator. 



beneath. A weighted accumulator is sometimes installed 
n connection with the oil pipe as a convenient device for 
governing the step-bearing pumps, and also as a safety 
ievice in case the pumps should fail, but it is seldom 
required f^r the fotter purpose, as the step-bearing pumos 



316 QUESTIONS AND ANSWERS 

have proven, after a long service in a number of cases 
to be reliable. The vertical shaft is also held in place an 
kept steady by three sleeve bearings, one just above th 
step, one between the turbine and generator, and th 
other near the top. These guide bearings are lubricate 
by a standard gravity feed system. It is apparent tha 
the amount of friction in the machine is very small, an 
as there is no end-thrust caused by the action of th 
steam, the relation between the revolving and stationar 
blades may be maintained accurately. As a consequence 
therefore, the clearances are reduced to the minimum 
The Curtis turbine is divided into two or more stage* 
and each stage has one, two or more sets of revolvin 
blades bolted upon the peripheries of wheels keyed to th 
shaft. There are also the corresponding sets of station 
ary blades, bolted to the inner walls of the cylinder o 
casing. 

Ques. 729. — What is the diameter of the vertical shaf 
for a 5,000 kilowatt turbine and dynamo? 

Ans. — Fourteen inches. 

Ques. 730. — How is the heat energy in the stean 
imparted to the wheel of the Curtis turbine? 

Ans. — Both by impulse and reaction. The steam i; 
admitted through expanding nozzles in which nearly all o: 
the expansive force of the steam is transformed into th< 
force of velocity. The steam is caused to pass throug 
one, two, or more stages of moving elements, each stag< 
having its own set of expanding nozzles, each succeedinj 
set of nozzles being greater in number and of larger are; 
than the preceding set. The ratio of expansion within 



STEAM TURBINE FUNDAMENTAL PRINCIPLES 317 

these nozzles depends upon the number of stages, as, for 
instance, in a two-stage machine the steam enters the 
initial set of nozzles at boiler-pressure, say 180 pounds. 
It leaves these nozzles and enters the first set of moving 
blades at a pressure of about 15 pounds, from which it 
further expands to atmospheric pressure in passing 




Fig. 194. One Stage of a 500 K. W. Curtis Steam Turbine in Course op 

Construction. 



through the wheels and intermediates. From the pres- 
ure in the first stage the steam again expands through 
the larger area of the second stage nozzles to a pressure 
slightly greater than the condenser vacuum at the 
entrance to the second set of moving blades, against 
which it now impinges and passes through, still doing 
work, due to velocity and mass. From this stage the 



318 



QUESTIONS AND ANSWERS 



steam passes to the condenser. If the turbine is a four 
stage machine and the initial pressure is 180 pounds, th< 
pressure at the different stages would be distributed ii 



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DD)»D])])D)DW])DD])DDDD])DD9 ~~*v*-*~ 




Atovmg B/acHes 






A#ov/r*£f JQ/o</GS 






cccccccccccccccccccccc 



M«t<«i<«H««i««« 



v**o vsin^ &/crc/G 9 



i 



I I ! I I I 

Fig. 195. 

Diagram of the nozzles, moving blades and stationary blades of a two-stag< 
Curtis steam turbine. The steam enters the nozzle openings at the top, controlle 
by the valves shown, two of the valves are open, and the course of the steal 
through the first stage is indicated by the arrows. 



18C 



about the following manner: Initial pressure, 18i 
pounds; fi-st sta^e, 50 pounds: second stage, 5 pounds 



STEAM TURBINE FUNDAMENTAL PRINCIPLES 319 

third stage, partial vacuum, and fourth stage, condenser 
vacuum. 

Ques. 731. — What are the diameters of the wheels? 

Ans. — The diameters of the wheels vary according to 
the size of the machine, that of a 5,000 kilowatt unit being 
13 feet. 

Ques. 732. — What amount of clearance is there be^ 
tween the revolving and stationary blades? 

Ans. — The clearance between the revolving and sta- 
tionary blades is from ?V to iV inch, thus reducing the 
wastage of steam to a very low percentage. 

Ques. 733. — Describe the action of the steam in a 
two-stage Curtis turbine. 

Ans. — The steam enters the nozzle openings at the top 
through valves that are controlled by the governor. 
After passing successively through the different sets of 
moving blades and stationary blades in the first stage, thq 
steam passes into the second steam-chest. The flow oj 
steam from this chamber to the second stage of bucket! 
is also controlled by valves, but the function of these 
valves is not in the line of speed-regulation, but for the 
purpose of limiting the pressure in the stage-chambers, 
in a manner somewhat similar to the control of the 
receiver pressure in a two-cylinder or three-cylinder 
compound reciprocating engine. The valves controlling 
the admission of steam to the second and later stages 
differ from those in the first group in that they partake 
more of the nature of slide-valves and may be operated 
either by hand or automatically; in fact, they require but 
very little regulation, as the governing is always done by 



320 



QUESTIONS AND ANSWERS 



the live-steam admission-valves. As previously stated, 
the steam first strikes the moving blades in the first stage 
of a two-stage machine at a pressure of about 15 pounds 




Fig. 196. Governor for 5,000 K. W. Turbine. 



above atmospheric pressure, but with great velocity. 
From this wheel it passes to the set of stationary blades 
between it and the next lower wheel. These stationary 
Wades change the direction of flow of the steam and cause 



STEAM TURBINE FUNDAMENTAL PRINCIPLES 321 

it to impinge against the buckets of the second wheel at 
the proper angle. 

Ques. 734. — How is speed-regulation accomplished in 
the Curtis steam turbine? 

Ans. — The governing of speed is accomplished in the 
first set of nozzles, and the control of the admission- valves 
here is effected by means of a centrifugal governor 
attached to the top end of the shaft. This governor, by 




Fig. 197. Electrically Operated Valve. 

a very slight movement, imparts motion to levers, which 
in turn work the valve mechanism. The admission of 
steam to the nozzles is controlled by piston-valves which 
are actuated by steam from small pilot-valves which are 
in turn under the control of the governor. Speed-regu- 
lation is effected by varying the number of nozzles in 
flow, that is, for light loads fewer nozzles are open and a 
smaller volume of steam is admitted to the turbine wheel, 
k*t the steam that is admitted impinges against the mov 



322 



QUESTIONS AND ANSWERS 



ing blades with the same velocity always, nz matter whetln 
the volume be large or small. With a full load and a 
the nozzle sections in flow, the steam passes to the whe 
in a broad belt and steady flow. 




Fig. 198. 5,000 Kilowatt Generating Umits. 

Comparison of space occupied and size of foundations. Modern Engii 
Type Unit and a Westinghouse-Parsons Turbine Type Unit of similar ratini 
and overload capacity. 



Ques. 735. — What great advantage does the steam 
turbine as a prime mover for an electric generatoi 
possess over the reciprocating engine? 

/Un. — The advantage of a high speed of revolution 



STEAM TURBINE — FUNDAMENTAL PRINCIPLES 323 

whereby there can be a great reduction in the size, 
weight, and cost of the direct-driven generator. 

Ques. 736. — Give approximately the over-all dimen- 
sions of a Westinghouse-Parsons turbo-generator unit of 
5,500-kilowatt, 11,000 volt capacity, of the revolving field 
type, speed 750 revolutions per minute, vacuum to be 
27/^2 inches. 

Ans. — Length 47 feet, width 13 feet, and height 
14 feet to top of gallery-ring. 




Fig. 199. General View oe a 400 K. W. Turbine Generator Unit. 



Ques. 737. — What amount of floor-space would a 
reciprocating engine and direct-connected generator of 
equal capacity with the above occupy? 

Ans. — The generator would be 42 feet in extreme 
diameter, its weight would be 445 tons (speed to be 75 
revolutions per minute) and it, together with the four- 
cylinder piston engine, would fill a space 40 feet wide by 
60 feet long, and tower 45 feet in height. 

Ques. 738. — Describe in general terms the construe* 



324 



QUESTIONS AND ANSWERS 



tion and principles of operation of the Westinghouse| 
Parsons steam-turbine. 

Ans. — The Westinghouse-Parsons steam-turbine il 
fundamentally based upon the invention of Mr. Charlej 
A. Parsons, who, while experimenting with a reactioi 
turbine constructed along the lines of Hero's engine, con« 
ceived the idea of combining the two principles, reactioi 




4&WPtfnttP r 




Fig. 200. Shows a 600 H. P. machine with the upper half of the cylinder, or 
stator as it is termed, thrown back for inspection. 

and impulse, and also of causing the steam to flow in a 
general direction parallel with the shaft of the turbine. 
This principle of parallel flow is common to all four types 
of turbines, but is perhaps more prominent in the 
Westinghouse-Parsons and less so in the De Laval. The 
cylinder, or stator, as it is termed, is divided longitudinally 
into an upper and a lower half flanged and bolted together. 
There are three sections or drums, gradually increasing 



STEAM TURBINE FUNDAMENTAL PRINCIPLES 325 

in diameter from the inlet to the third and last group of 
blades. This arrangement may be likened in some 
measure to the triple-compound reciprocating engine. 

Ques. 739. — Describe the arrangement of the blades 
or buckets in the Westinghouse-Parsons steam-turbine. 

Ans. — There are two kinds of blades, viz., stationary 
blades and moving blades, but they are similar in shape, 
being of the same curvature. These blades are made of 
hard drawn material, and are set into their places and 
secured by a caulking process. The stationary blades 
project from the inside surface of the cylinder, while 
similar rows of moving blades project from the surface 
of the rotor, or revolving drum. When the upper half 
of the cylinder is in position each row of stationary blades 
fits in between two corresponding rows of moving blades. 

Ques. 740. — Are these blades all of the same length? 

Ans. — They are not. The length varies from Yz inch 
for the shortest to 7 inches for the longest, according to 
their location. The shortest blades are placed at the 
steam end of each section and the longest blades are 
placed at the opposite end. 

Ques. 741. — What is the clearance between the blades 
as they stand in the rows? 

Ans. — The clearance between the blades as they stand 
in the rows is Y inch for the smallest size blades and Y* 
inch for the larger ones, gradually increasing from the 
inlet to the exhaust. In the 5,000 kilowatt machine the 
clearance at the exhaust end between the rows of blades 
is 1 inch. 

Ques. 742. — What is the general direction taken by 



326 



QUESTIONS AND ANSWERS 



the steam in its passage through the Westinghouse-Par 
sons turbine? 

Ans. — The steam entering at the smaller end of the 
cylinder presses first against the shortest blades and then 
passes on through in the form of spiral or screw line about 
the rotor, continually pressing against new and gradually 
lengthening blades, thus doing work by reason of its 
velocity. 



M ( ( f f (^f f STATIONARY BLADES. 

)) i )) D3 T¥T~ 



ccccccccc 

Z33HHB3 



MOVING BLADES 



STATIONARY BLADES 



^ 



MOVING BLADES 



Fig. 201. Section al View o* Four Rows of Blades, oe a Westinghouse 

Parsons Turbine. 

Ques. 743. — As steam presses equally in all directions, 
is there not a very heavy end-thrust exerted by the rotor? 

Ans. — There is not. The pressure in either direc- 
tion is perfectly balanced by means of balancing pistons 
placed on the steam end of the rotor. The diameters of 
these pistons correspond to the diameters of the different 
drums or sections.* 

Ques. 744. — About what is the velocity of the steam 
in the Parsons turbine? 



*The theory and action of these balancing pistons is fully 
and completely described in Swingle's "Twentieth Century Hand 
Bock for Engineers and Electricians." 



STEAM TURBINE FUNDAMENTAL PRINCIPLES 327 

Ans. — The highest velocity does not exceed 600 feet a 
second. 

Ques. 745. — About what amount of pressure is 
exerted upon each blade by the steam? 

Ans. — The steam-thrust on each blade is said to be 
equal to about 1 ounce avoirdupois. 

Ques. 746. — With such a very light pressure upon 




Fig. 202. Section al View off a Westinghouse-Parsons Turbine, Showing 
Arrangement of Balancing Pistons P. P. P. 



each blade, why is it that this turbine is capable of devel- 
oping power? 

Ans. — Because of the large number of blades; as, for 
instance, taking a 400 kilowatt machine, there are 16,095 
moving blades and 14,978 stationary blades, a total of 
31,073. 

Ques. 747. — How are the clearances preserved? 

Ans. — A rigid shaft and thrust or adjustment bearing 
accurately preserves the clearances. 



A 



328 QUESTIONS AND ANSWERS 

Ques. 748. — Describe the construction and action o 
the bearings. 

Ans. — The bearings are constructed along lines differ- 
ing from those of the ordinary reciprocating engine. Th< 
bearing proper is a gun-metal sleeve that is preventec 
from turning by a loose-fitting dowell. Outside of this 
sleeve are three concentric tubes having a small clearano 
between them. This clearance is kept constantly filled 
with oil supplied under light pressure, which permits a 
vibration of the inner shell or sleeve and at the same time 
tends to restrain or cushion it. This arrangement allows 
the shaft to revolve about its axis of gravity instead of 
the geometrical axis, as would be the case if the bearing 
were of the ordinary construction. The journal is thus 
to a certain degree a floating journal, free to run slightly 
eccentric according as the shaft may happen to be out of 
balance. 

Ques. 749. — How is the power of the Westinghouse- 
Parsons turbine transmitted to the dynamo, or other 
machine to be run? 

Ans. — A flexible coupling is provided, by means of 
which the power of the turbine is transmitted to the 
dynamo or other machine it is intended to run. The oi 
from all the bearings drains back into a reservoir, and 
from there it is forced up into a chamber, where is forms 
a static head, which giv^s a constant pressure of oil on 
all the bearings. 

Ques. 750. — How is the speed governed? 

Ans. — The speed of the Westinghouse-Parsons 
turbine is regulated by a fly-ball governer constructed in 



STEAM TURBINE FUNDAMENTAL PRINCIPLES 329 

such manner that a very slight movement of the balls 
serves to produce the required change in the supply of 
steam. The ball levers swing on knife edges instead of 
pins. The governor works both ways, that is to say, 
when the levers are oscillating about their mid position a 
head of steam corresponding to full load is being admitted 
to the turbine, and a movement from this point, either up 
or down, tends to increase or to decrease the supply of 
steam. 




Fig. 203. Section oe Westinghouse-Parsons Turbine Governor. 

Ques. 751. — What can be said of the efficiency of the 
Westinghouse-Parsons steam-turbine? 

Ans. — Under test a 400 kilowatt Westinghouse-Par- 
sons steam-turbine, using steam at 150 pounds initial 
pressure and superheated about 180 degrees, consumed 
11.17 pounds of steam per brake horse-power hour at full 
load. The speed was 3,550 revolutions per minute and 
the vacuum was 28 inches. With dry saturated steam 



A 



330 QUESTIONS AND ANSWERS 

the consumption was 13.5 pounds per brake horse-powei 
hour at full load, and 15.5 pounds at one-half load. A 
1,000 kilowatt machine, using steam of 150 pounds pres- 
sure and superheated 140 degrees, exhausting into c 
vacuum of 28 inches, showed the very remarkabl< 
.economy of 12,66 pounds of steam per electrical horse- 
power per hour. A 1,500 kilowatt Westinghouse-Par 
son turbine, using dry saturated steam of 150 pounds 
pressure with 27 inches vacuum, consumed 14.8 pounds 
steam per electrical horse-power hour at full load, anc 
17.2 pounds at one-half load. 

Ques. 752. — What efficiency does the Curtis turbini 
show in the use of steam? 

Ans. — A 600 kilowatt Curtis turbine operating at 
1,50P revolutions per minute, with steam at 140 pounds 
gaugt-pressure and 28.5 inches vacuum, showed a steam- 
consumption as follows, steam superheated 150 degrees: 
At full load, 12.5 pounds per electrical horse-power per 
hour; at half load, 13.25 pounds per electrical horse-power 
per hour; at one-sixth load, 16.2 pounds per electrica 
horse-power per hour, and at one-third overload, 12.4 
pounds per electrical horse-power per hour. 
| Ques. 753. — Describe in brief terms the Hamilton* 
Holzwarth steam-turbine. 

Ans. — The Hamilton-Holzwarth steam-turbine is 
based upon and has been developed from the designs of 
Prof. Rateau, and is being manufactured in this country 
by the Hooven-Owens-Rentschler Company, of Hamilton, 
Ohio. It is horizontal and placed upon a rigid bed-plate 
of the box pattern. AH steam, oil and water-pipes are 



STEAM TURBINE FUNDAMENTAL PRINCIPLES 331 

within and beneath this bed-plate, as are also the steam- 
mlet-valve and the regulating and by-pass valves. The 
smaller sizes of this turbine are built in a single casing or 
cylinder, but for units of 750 kilowatts and larger the 
revolving element is divided into two parts, high and low 
pressure. This turbine resembles the Westinghouse-Par- 
sons turbine in some respects, prominent of which is that 
it is a full-stroke turbine, that is, that the steam flows 
through it in one continuous belt or veil in screw line, 
the general direction being parallel with the shaft. But, 
unlike the Parsons type, the steam in the Hamilton-Holz- 
warth turbine is made to do its work only by impulse, 
and not by impulse and reaction combined. It might 
thus be termed an action turbine. 

Ques. 754. — Describe the interior construction of this 
turbine. 

Ans. — The interior of the cylinder is divided into a 
series of stages by stationary disks which are set in 
grooves in the cylinder and are bored in the center to 
allow the shaft, or rather the hubs of the running wheels 
that are keyed to the shaft, to revolve in this bore. 
There are no balancing pistons in this machine, the axial 
thrust of the shaft being taken up by a thrust ball-bear- 
ing. Between each two stationary disks there is located 
a running wheel, and the clearance between the running^ 
vanes and the stationary vanes is made as slight as is' 
consistent with safe practice. 

Ques. 755. — Describe the construction of the running 
vanes and the action of the steam upon them. 

Ans. — The running vanes conform in section somewhat 



332 



QUESTIONS AND ANSWERS 



to the Parsons type, but the action of the steam upon 
them and also within the stationary vanes is different. The 
expansion of the steam and 
consequent development of 
velocity takes place entirely 
within the stationary vanes, 
which also change the direc- 
tion of flow of the steam and 
distribute it in the proper 
manner to the vanes of the 
running wheels, which, ac- 
cording to the claims of the 
makers, the steam enters 
and leaves at the same pres- 
sure, thus allowing the 
wheel to revolve in a uni- 
form pressure. 

Ques. 756.— What pro- 
vision is made in the Hamil- 
ton-Holzwarth turbine for 
maintaining the velocity of 
the steam as it expands? 

Ans. — The first station- 
ary disk of the low-pressure 
turbine has guide-vanes all 
around its circumference, 
so that the steam enters the --a*-^ 

turbine in a full cylindrical belt, interrupted only by the 
guide-vanes. To provide for the increasing volume as 
the steam expands in its course through the turbine, the 




STEAM TURBINE-— FUNDAMENTAL PRINCIPLES 333 

areas of the passages through the distributers and running 
vanes must be progressively enlarged. The gradual in- 
crease in the dimensions of the stationary vanes permits 
the steam to expand within them, thus tending to maintain 
its velocity, while at the same time the vanes guide the 
steam under such a small angle that the force with which 
it impinges against the vanes of the next running wheel 
is as effective as possible. The curvature of the vanes is 
such that the steam while passing through them will in- 
crease its velocity in a ratio corresponding to its oper- 
ation. 

Ques. 757. — Describe the method of regulating the 
speed of this turbine. 

Ans. — The governor is of the spring and weight type, 
adapted to high speed, and is designed especially for 
turbine governing. It is directly driven by the turbine- 
shaft, revolving with the same angular velocity. Its action 
is as follows: Two disks keyed to the shaft, drive, by 
means of rollers, two weights sliding along a cross-bar 
placed at right angles through the shaft and compressing 
two springs against two nuts on the cross-bar. Every 
movement of the weights, caused by increasing or decreas- 
ing the angular velocity of the turbine-shaft, is trans- 
mitted by means of levers to a sleeve which actuates the 
regulating mechanism. These levers are balanced so that 
no back pressure is exerted upon the weights. The whole 
governor is closed in by the disks, one on each side, and a 
steel ring secured by concentric recesses to the disks. In 
order to decrease the friction within the governor and 
regulating mechanism, thrust ball-bearings and friction- 
less roller-bearings are us*d 



334 QUESTIONS AND ANSWERS 

Ques. 758.— Describe the action of the steam within 

t\\3 Hamilton-Holzwarth steam-turbine. 

Ans. — After leaving the steam-separator that is 
located beneath the bed-plate, the steam passes through 
the inlet or throttle-valve, the stem of which extends up 
through the floor near the high-pressure casing and is 
protected by a floor-stand and equipped with a hand 
wheel. The steam now passes through the regulating 
valve, which will be described later on. From this valve 
it is led through a curved pipe to the front head of the 
high-pressure casing or cylinder. In this head is a ring 
channel into which the steam enters, and from whence it 
flows through the first set of stationary vanes. 

Ques. 759. — Describe the action of the steam as it 
passes through the first set of stationary vanes. 

Ans. — In these vanes the first stage of expansion 
occurs, the velocity of the flow is accelerated, and the 
direction of flow is changed by the curve of the vanes in 
such manner that the steam impinges against the vanes 
of the first running wheel at the proper angle and in a full 
cylindrical belt, imparting by impulse a portion of its 
energy *o the wheel. 

Ques. 760. — What takes place in the course of the 
steam after leaving the first running wheel? 

Ans. — Passing through the vanes of this wheel, the 
steam immediately enters the vanes of the second station- 
ary disk, which are larger in area than those of the first, 
and here occurs the second stage of expansion, another 
acceleration of velocity, and also the proper change in 
direction, and the steam leaves this distributer and 



STEAM TURBINE FUNDAMENTAL PRINCIPLES 335 

impinges against the vanes of the second running wheel. 
This cycle is repeated throughout the several stages of 
the turbine, a certain percentage of the heat energy in the 
steam being imparted by impulse to each wheel and thence 
to the turbine-shaft. From the last running wheel the 
steam is led through receiver pipes to the front head of 
the low-pressure cylinder, or, if there is but one cylinder, 
directly to the condenser or the atmosphere. 

Ques. 761. — Describe the construction and location 
of the regulating valve. 

Ans. — The regulating valve is .located beneath the 
bed-plate. One side of it is connected by a curved pipe 
with the front head of the high-pressure cylinder and the 
other side is connected with the inlet-valve. The regulat- 
ing valve is of the double-seated poppet-valve type. 
Valves and valve-seats are made of tough cast steel, to 
avoid corrosion as much as possible, and the valve-body 
is made of cast iron. 

Ques. 762. — Describe the by-pass regulating valve. 

Ans. — This valve is also a double-seated poppet-valve 
and is located immediately below the regulating valve and 
forming a part of it. Thus the use of a second stuffing 
box for the stem of -this valve is avoided. The function 
of this valve is to control the volume of the live-steam 
supply that flows directly to the by-pass nozzles in the 
front head of the low-pressure casing. 

Ques. 763. — How is the main regulating valve 
operated? 

Ans. — The main regulating valve is not actuated 
directly by the governor, but by means of the regulating 
mechanism. 



336 QUESTIONS AND ANSWERS 

Ques. 764. — Describe the construction and operation 
of the regulating mechanism of the Hamilton-Holzwarth 
steam-turbines. 

Ans. — The construction and operation of this regulat- 
ing mechanism is as follows: The stem of the regulating 
valve is driven by means of bevel gears by a shaft that is 
supported in frictionless roller-bearings. On this shaft 
there is a friction wheel that the governor can slide across 
the face of a continuously revolving friction disk by 
means of its sleeve and bell-crank lever. This revolving 
disk is keyed to a solid shaft which is driven by a coupling 
from a hollow shaft. This hollow shaft is driven by the 
turbine-shaft through the medium of a worm gear. The 
solid shaft, with the continuously revolving friction disk, 
can be slightly shifted by the governor sleeve so that the 
two friction disks come into contact when the sleeve 
moves, that is, when the angular velocity changes. If 
this change is relatively great, the sleeve will draw the 
periodically revolving friction disk far from the center of 
the always revolving one, and this disk will quickly drive 
the stem of the regulating valve and the flow of steam will 
thus be regulated. As soon as the angular velocity falls 
below a certain percentage of the normal speed, the 
driving friction disk is drawn back by the governor, the 
regulating valve remains open and the whole regulating 
mechanism rests or stops, although the shaft is still 
running. 

Ques. 765. — Under what conditions will this governor 
shut down the turbine? 

Ans. — Should the angular velocity of the shaft reach 



STEAM TURBINE FUNDAMENTAL PRINCIPLES 33? 

a point 2.5 per cent higher than normal, the governor will 
shut down the turbine. If an accident should happen to 
the governor, due to imperfect material or breaking or 
weakening of the springs, the result would be a shut- 
down of the turbine. 

Ques. 766. — How may the speed of this turbine be 
changed, while running, if necessary? 

Ans. — In order to change the speed of the turbine 
while running, which might be necessary in order to run 
the machine parallel with another prime mover, a spring 
balance is provided, attached to the bell-crank lever of 
the regulating mechanism. The hand-wheel of this spring 
balance is outside of the pedestal for regulating mechanism 
and near the floor-stand and hand-wheel. With this 
spring balance the speed of the turbine may be changed 
5 per cent either way from normal. 

Ques. 767. — What is the best method of disposing of 
the exhaust steam of steam-turbines? 

Ans. — As in the case of the reciprocating engine, the 
highest efficiency in the operation of the steam-turbine is 
obtained by allowing the exhaust steam to pass into a 
condenser, and experience has demonstrated that it is 
possible to maintain a higher vacuum in the condenser of 
a turbine than in that of a reciprocating engine. This 
is due, no doubt, to the fact that in the turbine the steam 
is expanded down to a much lower pressure than is pos- 
sible with the reciprocating engine. 

Ques. 768. — What type of condensing apparatus is 
best adapted to steam-turbines? 

Ans. — The condensing apparatus used in connection 



338 QUESTIONS AND ANSWERS 

with steam-turbines may consist of any one of the 
modern improved systems, and as no cylinder-oil is usetf 
within the cylinder of the turbine, the water of condensa- 
tion may be returned to the boilers as feed-water. If the 
condensing water is foul or contaii-J matter that would 
be injurious to the boilers, a surface condenser should be 
used. If the water of condensation is not to be used in 
the boilers, the jet system may be employed. 

Ques. 769. — What percentage of gain may be effected 
by allowing the exhaust steam from the turbine to pass 
into a good condenser? 

Ans. — As an instance of the great gain in economy 
effected by the use of the condenser in connection with 
the steam-turbine, a 750 kilowatt YYestinghouse-Parsons 
turbine, using steam of 150 pounds pressure, not super- 
heated and exhausting into a vacuum of 28 inches, showed 
a steam consumption of 13.77 pounds per brake horse- 
power per hour, while the same machine operating non- 
condensing consumed 28. 2G pounds of steam per brake 
horse-power hour. Practically the same percentage in 
economy effected by condensing the exhaust applies to 
the other types ofsteam-turbines. 

Ques. 770. — About what is the additional cost of 
operating a complete condensing outfit in connection 
with a steam-turbine plant? 

Ans. — With reference to the relative cost of operating 
the several auxiliaries necessary to a complete condensing 
outfit, the highest authorities on the subject place the 
power consumption of these auxiliaries at from 2 to 7 per 
cent of the total turbine output of power. A portion of 



STEAM TURBINE FUNDAMENTAL PRINCIPLES 339 

this is regained by the use of an open heater for the feed- 
water, into which the exhaust steam from the auxiliaries 
may pass, thus heating the feed-water and returning a 
part of the heat to the boilers. 

Ques. 771. — What precautions must be observed in 
the operation of a condensing outfit in order to obtain the 
highest efficiency? 

Ans. — A prime requisite to the maintenance of high 
vacuum, with the resultant economy in the operation of 
the condensing apparatus, is that all entrained air must 
be excluded from the condenser. There are various ways 
in which it is possible for air to find its way into tne con- 
densing system. For instance, there may be an improp- 
erly packed gland, or there may be slight leaks in the 
piping, or the air may be introduced with the condensing 
water. This air should be removed before it reaches the 
condenser, and it may be accomplished by means of the 
"dry" air-pump. 

Ques. 772. — Describe some of the leading character- 
istics of the dry air-pump. 

Ans. — This dry air-pump is different from the 
ordinary air-pump that is used in connection with most 
1 condensing systems. The dry air-pump handles no 
water, the cylinder being lubricated with oil in the same 
nanner as the steam-cylinder. The clearances also are 
made as small as possible. These pumps are built either 
in one or two stages. 

Ques. 773. — What particular features would be 
required in the design of a compound or stage-expansion 
reciprocating engine, in order to develop a high vacuum, 
tor instance a* huri»*s-?'H> '*"*hes? 



340 QUESTIONS AND ANSWERS 

Ans. — In comparing the efficiency of the reciprocating 
engine and the steam-turbine it is not to be inferred that 
reciprocating engines would not give better results at 
high vacuum than they do at the usual rate of 25 to 26 
inches, but to reach and maintain the higher vacuum of 
28 to 28.5 inches with the reciprocating engine would 
necessitate much larger sizes of the low-pressure cylinder, 
as also the valves and exhaust pipes, in order to handle 
the greatly increased volume of steam at the low-pressure 
demanded by high vacuum. 

Ques. 774. — What advantage has the turbine over the 
reciprocating engine, in the disposal of its exhaust 
steam? 

Ans. — The steam-turbine expands its working steam 
to within 1 inch of the vacuum existing in the condenser, 
that is, if there is a vacuum of 28 inches in the condenser 
there will be 27 inches of vacuum in the exhaust end of 
the turbine cylinder. On the other hand, there is usually 
a difference of 4 or 5 inches (2 to 2.5 pounds) between 
the mean back pressure in the cylinder of a reciprocating 
condensing engine and the absolute back pressure in the 
condenser. 

Ques. 775. — Mention the two principal sources of 
economy that the steam-turbine possesses in a high 
degree. 

Ans. — Two of the main sources of economy that the 
steam-turbine possesses in a much higher degree than 
does the reciprocating engine are: First, its adaptability 
for using superheated steam, and second, the possibility 
of maintaining a higher degree of vacuum. 



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342 QUESTIONS AND ANSWERS 

Ques. 776. — What can be said of the steam turbine, 
regarding friction of rubbing parts, such as reciprocating 
pistons, cross-heads, etc? 

Ans. — There are no rubbing surfaces in the turbin 
except the bearings of the rotor. 

Ques. 777. — Of what type is the Allis Chalmers steam- 
turbine? 

Ans. — It is of the reaction, or Parsons type, with a 
number of modifications in details of construction. 

Ques. 778. — Give an elementary description of the 
"Parsons" steam-turbine. 

Ans. — It consists essentially of a fixed casing, or 
cylinder, usually arranged in three stages of different 
diameters, that of the smallest diameter being at the high- 
pressure, or admission end, and that of the largest diam- 
eter at the low-pressure or exhaust end of the casing. 

Inside of this casing is a revolving drum, or rotor, the 
ends of which are extended in the form of a shaft, and 
carried in two bearings, just outside each end of the cyl- 
inder. 

Ques. 779. — What causes the drum to revolve within 
the cylinder? 

Ans. — The drum is fitted with a large number of small 
curved blades, or paddles arranged in straight rows 
around its circumference. The blades in each stage, or 
step, are also arranged in groups of increasing length, 
those at the beginning of each larger stage being shorter 
than those at the end of the preceding stage, the change 
being made in such a manner that the correct relation of 
blade length to drum diameter is secured. These rows of 



STEAM TURBINE FUNDAMENTAL PRINCIPLES 343 

revolving blades fit in and run between corresponding 
rows of stationary blades that project from the walls of 
the cylinder. These stationary blades have the same cur- 
vature as the revolving blades, but are set so that the 
curves incline in the opposite direction to those of the 
revolving blades. The steam entering the cylinder at the 
smallest or first stage, is deflected in its course by the 
first row of stationary blades, and immediately impinges 
with a pressure but slightly reduced from boiler pressure, 
against the first row of revolving blades. It then passes 




EXHAUST 



FIG.I 

ELEMENTARY PARSONS TYPE STEAM TURBINE 



Fig. 206. 



Main bearings, A and B. Thrust bearing, R. Steam pipe, C. Main throttle 
valve, D. which is balanced, and operated by the governor. Steam enters the 
cylinder through passage E, passes to the left through the alternate rows of 
stationary and revolving blades, leaving the cylinder at F and passes into the 
condenser, or atmosphere through passage G. H, J and K are the three steps or 
stages of the machine. L,, M and N are the three balance pistons. O, P and 
Q are the equalizing passages, connecting the balance pistons with the corres- 
ponding stages. 



to the next row of stationary blades, which again deflect 
its course so as to cause it to strike the next row of mov- 
ing blades at the proper angle. Thus the continual 
pressure and reaction of the steam against the cuivetf 
surfaces of the moving blades causes the drum, or rotor 
to revolve. 




Pic 207. Spindle or Rotor, Aixis Chalmers Steam Turbine. 
The rings which carry the blades are pressed on. 



^ 



STEAM TURBINE FUNDAMENTAL PRINCIPLES 



345 



Ques. 780. — Does not the action of the steam against 
the revolving blades tend to produce a strong end thrust? 
Ans. — It does — but this thrust is neutralized by three 
"balance-pistons" so called, which are fitted upon the 
revolving drum at the high-pressure end of the cylinder. 
The diameter of each "piston" corresponds with the 
diameter of that stage of the cylinder with which it is 
connected by an equalizing passage which permits the 
steam to act upon it, and thus balance the thrust. 




Fig. 208. 

Fig. 208 showing arrangement of blading and course of the steam in Parson* 
iteam turbine. 



Ques. 781. — Do the revolving blades come in contact 
ith the stationary parts? 
Ans. — They do not. The high speeds which are nec- 
essary in the steam turbine prohibit any continuous con- 



346 



QUESTIONS AND ANSWERS 



tact between moving and stationary parts, except in the 
lubricated bearings. 

Ques. 782. — How much clearance is allowed between 
the moving and stationary parts in the "Parsons" steam- 
turbine? 

Ans. — The tips of the revolving blades just clear the 
walls of the cylinder, and the tips of the stationary blades 
just clear the surface of the rotor. 










B 


( R 













GUUU6T 



Fig. 209. 



Sectional view of elementary Parsons steam turbine, with Allis Chalmers 
modifications. L and M are the two balance pistons at the high pressure end. 
Z is a smaller balance piston placed in the low pressure end, yet having the 
same effective area as did the larger piston N shown in Fig. 206. O and Q are 
the two equalizing passages for. pistons L and M. Passage P is omitted in this 
construction and balance piston Z is equalized with the third stage pressure at 
Y. Valve V is a by-pass valve to allow of live steam being admitted to the 
second stage of the cylinder in case of a sudden overload. This by-pass valve is 
the equivalent of the by-pass valve used to admit live steam to the low pressure 
cylinder of a compound reciprocating engine. Valve V is arranged to be 
operated, either by the governor or by hand, as the conditions may require. 
Frictionless glands made tight by water packing are provided at S and T where 
the shaft passes out of the cylinder. The shaft is extended at U and connected 
to the generator shaft by a flexible coupling. 



Ques. 783. — How are the clearances between the 
edges of the revolving and stationary blades preserved? 

Ans. — The position of the drum, as regards end play, 
is definitely fixed by means of a small "thrust bearing" 
provided inside the housing of the main bearing. 

This so-called thrust bearing can be adjusted to locate* 



STEAM TURBINE — FUNDAMENTAL PRINCIPLES 347 

and hold the revolving spindle or rotor in such position as 
will allow sufficient clearance between the moving and 
stationary blades, and yet reduce the leakage of steam to 
a minimum. 

Ques. 784. — Is there not danger of out leakage of 
steam, and in leakage of air, where the shaft passes out 
of the high and low-pressure ends of the cylinder? 

Ans. — There is; but this is provided for by glands 
that are made practically frictionless by water packing, 
without metallic contact. 

Ques. 785. — How is the power of the "Parsons" type 
of steam-turbine transmitted to the electric generator, or 
other machine to be run? 

Ans. — The shaft is extended at the low-pressure end, 
nd coupled to the shaft of the generator by means of a 
lexible coupling. 

Ques. 786. — What provision is made in this type of 
team-turbine for speed regulation? 

Ans. — The speed of the "Parsons" turbine is regu- 
ated by a very sensitive governor driven from the turbine 
>haft by means of cut gears working in an oil bath. The 
jovernor operates a balanced throttle-valve, and may be 
idjusted for speed while the turbine is in motion if 
lecessary for the synchronizing of alternators, and divid-, 
ng the load. 

Ques. 787. — Suppose there should be an accidental 
ierangement of the governing mechanism, what provision 
s made for preventing dangerous over speed? 

Ans. — A separate safety governor is provided, driven 
iirectly by the turbine shaft, without the intervention of 



348 QUESTIONS AND ANSWERS 

gearing, and so adjusted that if the speed of the turbin 
should reach a predetermined point above that for whic 
the main governor is set, the safe:j governor will com 
into action, and trip a valve, thus shutting off the stean 
and stopping the turbine. 

Ques. 788. — Is the arrangement of "balance-pistons 
described in answer to question 780 carried out in a 
sizes of steam-turbines of the "Parsons" type? 

Ans. — No. In the larger sizes of the Allis Chalmer 
steam-turbine, the. largest one of the three pistons at th 
high-pressure end is replaced by a smaller balance-pistoi 
located at the low-pressure end of the turbine, and work 
ing inside a supplementary cylinder. 

This piston presents the same effective area for th< 
steam to act upon, as did the larger piston, because th« 
working area of the latter in its original location con 
sisted only of the annular area included between it 
periphery, and the periphery of the next smaller piston. 

Ques. 789. — How is the pressure of the steam brough 
to bear upon this equalizing piston in its new position? 

Ans. — By means of passages through the body of th< 
rotor, connecting the third stage of the cylinder wit 
the supplementary cylinder in which the piston revolves 

Ques. 790.— How are the blades or paddles fitted to 
and held in the rotor, and cylinder of the Allis Chalmen 
steam-turbine? 

Ans. — Each blade is individually formed by specia 
machine tools, so that its root or foot is of an angular 
dove-tail shape, and at its tip there is a projection. 

Foundation rings are provided for each row of blade*. 



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350 QUESTIONS AND ANSWERS 

These rings have slots of dove-tail shape cut into thei 
to receive the roots of the blades. These slots are accu 
rately spaced, and inclined so as to give the require 
pitch and angle to the blades. The foundation ring 
themselves are dove-tail in cross section, and are inserte 
in dove-tail grooves cut in the turbine cylinder, and roto 
respectively. These rings are firmly held in place by ke; 
pieces that are driven into place, and upset into undercu 
grooves, thus locking the whole structure firmly together 

Ques. 791. — How are the tips or outer ends of th 
blades protected? 

Ans. — By a shroud ring for each row, in which hole 
are punched to receive the projections on the tips of th 
blades. 

These holes are spaced by special machinery to mate 
the slots in the foundation ring. 

Ques. 792. — Describe the construction of the shrouc 
rings. 

Ans. — They are channel shaped in cross section, ant 
are made thin, so that in case of accidental contact wit 
an opposing surface no dangerous heating will occur 
neither will the rubbing be so liable to rip out the blades 
as it is when they are unprotected by a shroud ring. 

Ques. 793. — Mention another advantage in connectioi 
with the use of a shroud ring. 

Ans. — The blades in each row are stiffened, and hel( 
together as a unit by its use, thus permitting smalle 
clearances, and reducing the leakage loss to a minimum 
The channel shape of the shroud ring also forms ai 
effective baffle to the steam leakage. 




Fig. 211. 

Fig. 211 illustrates blades as fitted in the rotor of Allis Chalmers steam 
turbine. The shroud ring protecting the tips of the blades is also shown. 



352 



QUESTIONS AND ANSWERS 



Ques. 794. — What type of bearings are the Allis 
Chalmers steam-turbines fitted with? 

Ans. — Self-adjusting ball and socket bearings espe« 
cially designed for high speed, shims being provided for 
proper alignment. 




Fig. 212. 

Fig. 212 shows a number of rows of stationary blades fitted in the cylinder of 
an Allis Chalmers steam turbine. 

In the smaller sizes the bearing shells are made of 
special bronze, and in the larger sizes white metal is used 
for bearing surface. 



STEAM TURBINE FUNDAMENTAL PRINCIPLES 353 

Ques. 795. — How are these bearings lubricated? 

Ans. — The oil is supplied freely to the middle of each 
bearing, and allowed to flow out at the ends, where it is 
caught, passed through a cooler, and pumped back to the 
bearings, to be used again and again. 

Ques. 796. — Does the fact that the oil is supplied 
to the bearings in large quantities necessarily imply a 
heavy expenditure for oil? 

Ans. — It does not; for the reason that the bearings 
practically float on oil films, thus preventing that * 'wear- 
ing out" of the oil which occurs when it is supplied in 
diminutive doses. 

Ques. 797. — Can superheated steam be used to advan- 
tage in steam-turbines? 

Ans. — It can; in fact the steam-turbine has solved the 
problem of superheated steam, owing to the absence of 
all rubbing parts exposed to the steam. This permits the 
use of steam of high temperature thus making it possible 
to realize the advantages of economical operation. 

Ques. 798. — Is there not danger of distortion of the 
turbine cylinder being caused by the very high tempera- 
tures to which it is exposed by the use of superheated 
steam? 

Ans. — There have been numerous instances in the past 
of unequal expansion of the top, and bottom of the cylin- 
der thereby causing the rotating blades to come in 
contact with the cylinder walls, and be ripped out, but this 
difficulty has in a great measure been overcome by certain^ 
designers of steam-turbines, who have made a special 
study of the laws of expansion and contraction of metais> 



354 QUESTIONS AND ANSWERS 

and have thus been enabled to make such a distribution 
of the metal, as to cause an equal expansion of all parts 
of the cylinder. 

Ques. 799. — What effect does the accidental carrying 
over of water with the steam, have upon the steam-tur- 
bine? 

Ans. — The sudden presence of a quantity of water 
with the steam, caused by foaming or priming of the boil- 
ers, would cause no more serious results than the slowing 
down of the turbine during the time necessary to permit 
the water to be discharged from the exhaust end. 

Ques. 800. — What may be said in general of the 
steam-turbine? 

Ans. — It has passed through the experimental stage, 
and has come to the front, as an efficient power pro- 
ducer, having a bright future before it. 



DE LAVAL STEAM TURBINE. 

CLASS C. 

Ques. 801. — In what respect does the Class C De 
Laval Turbine differ mainly from the regulation type of 
De Laval Turbine referred to on pages 304 to 314? 

Ans. — In the construction of the buckets, and guide 
vanes ; also in the accessibility of the parts. 

Ques. 802. — Describe the construction of the buckets 
in this type of steam Turbine. 

Ans. — The buckets are made of nickel-bronze and 
are secured to the rim of the wheel by bulb shanks. 
They may also be replaced individually without disturb- 
ing other buckets. 



STEAM TURBINE FUNDAMENTAL PRINCIPLES 355 

Ques. 803. — Describe the construction of the guide 
vanes in the Class C Turbine . 

Ans. — The guide vanes are of nickel-bronze, and are 
attached to steel retaining rings in the same manner as 
are the rotating buckets. 

Ques. 804.— What can be said in favor of this meth- 
od of attaching guide vanes, and buckets ? 

Ans. — It is superior to the common method of cast- 
ing these important parts of the turbine in with a por- 
tion of the casing, or the rim of the wheel. 
Ques. 805. — Give a reason for this. 
Ans. — If guide vanes, or buckets that are cast in, 
should become corroded, and need replacing, it is neces- 
sary to replace a portion of the casing, or the wheel rim, 
in order to bring the turbine back to its original effi- 
ciency. 

Ques. 806. — What amount of work is necessary in 
order to replace one, or more of these parts in the Class 
C De Laval Steam Turbine? 

Ans. — See answer to question 802. 

Ques. 807. — How are changes in boiler pressure, or 
in vacuum, provided for in the Class C Turbine ? 

Ans. — By simply replacing the nozzles by others de- 
signed for the new ratio of expansion. 

Ques. 808. — Is this possible in turbines in which the 
nozzles are a permanent part of the main turbine struc- 
ture? 

Ans. — It is not. 

Ques. 809.— How is the speed of the Class C De 
Laval Turbine controlled? 



356 QUESTIONS AND ANSWERS 

Ans. — Two governors are provided, one of which is 
called the emergency governor. 

Ques. 810. — In what way may a turbine governor be 
rendered useless, and still retain all its parts unbroken? 

Ans. — By the valves becoming clogged with scale, 
waste or other foreign matter. 

Ques. 811. — What special provision does this type of 
steam turbine possess for the prevention of accidents in 
case the emergency governor should fail ? 

Ans. — The wheel itself is designed to withstand the 
highest speed, and in addition to this precaution, the en- 
tire wheel is encircled by a steel ring which would ef- 
fectually prevent the penetration of detached parts. 

Ques. 812. — How may the rotating parts of the 
De Laval Class C Turbine be removed entirely from the 
casing when repairs are necessary ? 

Ans. — By lifting the casing cover, and loosening and 
removing the bearing caps of the shaft. 

Ques. 813. — Why is it possible to maintain indefinite- 
ly a high steam economy with this type of steam tur- 
bine? 

Ans. — This is due to the fact that provision is made 
for the easy and quick replacement of those parts sub- 
ject to wear. 

Ques. 814. — Is the Type C De Laval Steam Turbine 
built in the larger sizes? 

Ans. — It is not, at present. 

Ques. 815. — Mention some of the principal uses fcr 
which this turbine is adapted. 

Ans. — It is especially adapted to the driving ol cen- 



STEAM TURBINE FUNDAMENTAL PRINCIPLES 357 

trifugal pumps, blowers, exciters, and small dynamos. 

Ques. 816. — Describe the various conditions of op- 
eration for which the Class C Steam Turbine is built. 

Ans. — It may be operated high pressure condensing, 
or high pressure non-condensing. It may also be op- 
erated with a certain degree of back pressure. Again, 
it may be operated as a low pressure condensing turbine, 
or it may be operated on mixed flow service. 



EXTRACTS FROM UNITED STATES GOVERN- 
MENT RULES FOR THE EXAMINATION 
OF APPLICANTS FOR ENGINEERS' 
LICENSE. 

Ques. 817. — Give some of the principal regulations 
relative to Marine Engineers. 

Ans. — Before an original license is issued to any per- 
son to act as engineer, he must personally appear be- 
fore some local board, or a supervising inspector for 
examination; but upon the renewal of such license, 
when the distance from any local board, or supervising 
inspector is such as to put the person holding the same 
to great inconvenience, and expense to appear in person, 
he may upon taking the oath of office before any per- 
son authorized to administer oaths, and forwarding the 
same, together with the license to be renewed, to the 
local board, or supervising inspector of the district in 
which he resides, or is employed, have the same renewed 
by the said inspectors, if no valid reason to the contrary 
be known to them, and they shall attach such oath to 
the stub end of the license, which is to be retail *n 



358 QUESTIONS AND ANSWERS 

f}le in their office. And inspectors are directed, when 
licenses are completed, to draw a broad pen and ink red 
mark through unused spaces in the body thereof, so as 
to prevent a6 far as possible, illegal interpolation after 
issue. 

Ques. 818. — Give in brief the classification of engi- 
neers on the lakes, and seaboard. 

Ans. — The classification of engineers on the lakes, 
and seaboard shall be as follows : 

Chief Engineer. 

First Assistant Engineer. 

Second Assistant Engineer. 

Third Assistant Engineer. 

Ques. 819. — What limitations are placed upon chief 
engineers, and assistant engineers relative to their 
spliere of action? 

Ans. — Inspectors may designate upon the certificate 
of any chief, or assistant engineer the tonnage of the 
vessel on which he may act." 

Ques. 820. — What additional restrictions are placed 
upon assistant engineers? 

Ans. — First, second, and third assistant engineers 
may act as such on any steamer of the grade of which 
they hold a license, or as such assistant engineer on any 
sfeamer of a lower grade than those to which they hold 
a license. 

Ques. 821. — On what grades of steamers may assist- 
ant engineers act as chief engineers? 

Ans. — Assistant engineers may act as chief engi- 
neers on high pressure steamers of one hundred tons bur- 



STEAM TURBINE FUNDAMENTAL PRINCIPLES 359 

den and under, of the class and tonnage, or particular 
steamer for which the inspectors, after a thorough ex- 
amination, may find them qualified. In all cases where 
an assistant engineer is permitted to act as first (chief) 
engineer, the inspector shall state on the face of his cer- 
tificate of license, the class and tonnage of steamers, or 
the particular steamer on which he may so act. 

Ques. 822. — What is the duty of an engineer when 
he assumes charge of the boilers and machinery of a 
steamer ? 

Ans. — His duty is to forthwith thoroughly examine 
the same, and if he finds any part thereof in bad con- 
dition, caused by neglect or inattention on the part of 
his predecessor, he shall immediately report the facts to 
the local inspectors of the district, who shall thereupon 
investigate the matter, and if the former engineer has 

been culpably derelict of duty, they shall suspend or re- 

i 

voke his license. 

Ques. 823. — What are some of the important require- 
ments regarding service that will entitle a person to re- 
ceive an original license as engineer or assistant engi- 
neer? 

Ans. — He must have served at least three years in 
the engineers' department of a steam vessel; provided 
that any person who has served as a regular machinist 
in a marine engine works for a period of not less than 
three years ; and any person who has served for a period 
of not less than three years as a locomotive engineer, 
stationary engineer, regular machinist in a locomotive, 
or stationary engine works, and any person who has 



360 QUESTIONS AND ANSWERS 

graduated as a mechanical engineer from a duly recog- 
nized school of technology, may be licensed as engineer 
on steam vessels, after having had not less than one 
year's experience in the engine department of a steam 
vessel. 

Ques. 824. — What are the requirements regarding 
education? 

Ans. — No original license shall be granted any engi- 
neer, or assistant engineer, who cannot read and write, 
and does not understand the plain rules of arithmetic. 

Ques. 825. — What are the requirements regarding 
the age of an applicant? 

Ans. — He must be not less than twenty-one, nor more 
than thirty years of age in order to receive an appoint- 
ment as second assistant engineer. 

Ques. 826. — What is the penalty for making a false 
statement before a board of examination, or of produc- 
ing a false certificate as to age, time of service or char- 
acter? 

Ans. — Any person found guilty of such action will 
be dropped immediately. 



CHAPTER XI 

MODERN TYPES OF OIL ENGINES 

Ques. 827. — What is the propelling force behind the 
piston of an oil engine? 

Ans. — The heat energy evolved by the combustion of 
a mixture of vaporized fuel oil and air under compres- 
sion. 

Ques. 828. — How is the vaporization of the oil accom- 
plished ? 

Ans. — There are four methods, classified as follows: 
(1) Vaporization caused by the heat evolved by the en- 
gine. (2) Vaporization in an external chamber which is 
heated from external sources. (3) Vaporization in an 
internal chamber heated wholly or in part from external 
sources. (4) Combustion caused by the heat of highly 
compressed air, without previous vaporization of the oil. 

Ques 829. — Which one of these methods of vaporiza- 
tion has proved to be the most practicable and best 
adapted to all conditions of service? 

Ans. — The one belonging in class 4, owing to its sim- 
plicity and the absence of much auxiliary equipment, vap- 
orization taking place within the cylinder itself. 

Ques. 830. — Explain the principles of a two-cycle oil 
engine. 

Ans. — A two-cycle engine receives a charge of the 

:xplosive mixture, compresses it, ignites it and discharges 

he products of combustion while the piston makes one 

361 



362 QUESTIONS AND ANSWERS 

complete travel backward and forward. Consequently 
it has a working stroke or power impulse for each revo- 
lution of the crank shaft. 

Ques. 831. — Explain the principles of a four-cycle oil 
engine. 

Ans. — The four-cycle engine requires four strokes of 
the piston, or two revolutions of the crank shaft to com- 
plete the cycle. Consequently there is but one power im- 
pulse for every two revolutions of the crankshaft, or one 
working piston stroke out of four. 

Ques. 832. — Which is the most simple type from a 
constructive point of view? 

Ans. — The four-cycle engine. 

Ques. 833. — Give reasons for this. 

Ans. — The two-cycle engine requires a scavenging air 
pump to discharge the exhaust gases ; also special devices 
for the admission of cooling water to the piston. In the 
four-cycle engine this apparatus is not required. 

Ques. 834. — Which type of engine is the most eco- 
nomical in the use of fuel oil? 

Ans. — The fuel consumption per brake horsepower 
of a four-cycle engine is from 7 to 10 per cent less than 
that of the two-cycle engine. 

Ques. 835. — To which one of the four classes of oil 
engines as enumerated in the answer to Question 828 
does the Diesel Engine belong? 

Ans. — To class 4. 

Ques. 836. — How is combustion effected in the Diesel 
oil engine? 



MODERN TYPES OF OIL ENGINES 363 

Ans.— The Diesel engine admits a large volume of air 
to the cylinder and compresses it to such an extent that 
upon the introduction of oil in the form of spray by a 
blast of air at still higher pressure, combustion occurs at 
once without previous admixture. 

Ques. 837.— Explain in brief the action taking place 
within the cylinder of a Diesel engine at the beginning of 
a power stroke. 

Ans. — The oil fuel is injected through the fuel valve 
located in the top of the cylinder, which is vertical. This 
valve is opened by a cam just before the piston has 
reached its top center, and the injection of the fuel then 
commences and continues until the piston after passing 
the top dead center has moved through about 10 per cent 
of its downward stroke. Owing to the high pressure now 
prevailing in the combustion chamber, which is that por- 
tion of the cylinder space above the piston a tempera- 
ture is produced which exceeds the ignition point of the 
fuel oil, and as a result the oil, having entered the cylin- 
der in an extremely pulverized state, is at once ignited, 
and is combusted under approximately constant pressure. 

Ques. 838. — How is this constant pressure maintained 
during the period of oil admission ? 

Ans. — In two ways. First, by the compression pres- 
sure exerted by the piston on its up-stroke ; second, by the 
admission of compressed air under a pressure exceeding 
that of compression this air is required for the injection 
of the charge of fuel oil. 

Ques. 839.— What pressure is usually required for 



364 QUESTIONS AND ANSWERS 

injection of the fuel oil into the combustion chamber of 
an oil engine of the Diesel type? 

Ans. — From 450 to 600 lbs. per sq. in., depending 
upon the style or make of the engine, and also upon local 
conditions. 

Ques. 840. — From whence is this supply of com- 
pressed air obtained? 

Ans. — From one or more high pressure air compres- 
sors usually driven from the main crosshead of the en- 
gine by means of links and beams. 

Ques. 841. — How many working cylinders are there in 
the ordinary Diesel oil engine? 

Ans. — Four, and in some cases six. 

Ques. 842. — Give a brief description of the construc- 
tion and action of the high pressure air compressors al- 
ready referred to. 

Ans. — They are of the tandem compound type, two 
or three stage, the low pressure stage being double acting, 
while the intermediate and high pressure stages are single 
acting. Cooling coils are provided for each stage. The 
piston and discharge valves of the low r pressure stage are 
of the flat disk type, while those of the higher stages are 
of the poppet type. The high pressure air is delivered to 
a pipe, common to all the cylinders of the engine. This 
pipe conveys the air through separators to the spray-air 
bottle from whence it leads to the fuel inlet valve bodies 
in the cylinder heads. 

Ques. 843. — What is the function of the spray-air 
bottle? 



MODERN TYPES OF OIL ENGINES 365 

Ans.— The spray-air bottle has an overflow valve 
whereby air in excess of that necessary for spraying is 
passed into a bottle for storing the starting air. 

Ques. 844.— What is meant by the expression "start- 
ing air" as used in conection with the Diesel oil engine ? 

Ans.— In starting the engine, compressed air at about 
650 lbs. pressure is admitted to those cylinders whose 
cranks are in the proper position for running in the de- 
sired direction. After the engine begins to turn, starting 
air is admitted to each cylinder from 10 degrees past the 
top center to 85 degrees past the top center until the en- 
gine has attained sufficient speed for fuel admission, 
(These remarks apply to the two-cycle type.) 

Ques. 845.— Give further details regarding the process 
of starting. 

Ans. — Just before fuel admission occurs clean air 
from the scavenging receiver has been compressed in 
the working cylinders to about 450 lbs. pressure, and 
when the engine is running normally fuel admission to 
each cylinder occurs as follows : When the piston on the 
up stroke is within 2^ degrees of the top center the fuel 
admission valve opens and remains open until the piston 
has reached a point $jy 2 degrees past the top center 
when the valve closes and combustion takes place. 

Ques. 846. — Describe events in connection with the 
exhaust. 

Ans.— The exhaust ports are uncovered 35 degrees 
before the piston has reached bottom center, and 2^ 
degrees before the exhaust ports start to be uncovered, 



366 QUESTIONS AND ANSWERS 

two scavenger valves in the cylinder head are opened by 
the cam shaft, admitting fresh air at 7 or 8 lbs. pressure 
to the cylinder for scavenging. The exhaust ports are 
ag f ain covered by the piston at 35 degrees past bottom 
center, and compression begins. 

Ques. 847. — What length of time do the scavenger 
valves remain open ? 

Ans. — Until 31^ degrees after the exhaust ports are 
closed by the piston, from which point compression oc- 
curs until 2j4 degrees before the top center is reached, 
when the fuel valve opens as stated in answer to ques- 
tion 845. 

Ques. 848. — How is the speed of the Diesel oil engine 
regulated ? 

Ans. — By the control of certain factors in connection 
with its operation, as for instance, the amount of fuel 
injected, the amount and pressure of the compressed air 
required for vaporizing and injecting the fuel, also the 
variable admission of fuel by the vaporizer valve in ac- 
cordance with the amounts of air and fuel. 

Ques. 849. — What means are employed for controlling 
the amount of fuel, and the pressure of the injection air? 

Ans. — These factors are adjusted directly from the 
regulator. The air pressure supply is controlled by ad- 
justing a slide fitted into the suctions of the low or first 
stage cylinders of the air compressor. The quantity and 
pressure of the spray or injector air is thus easily regu- 
lated. The duration of opening of the fuel valve is ad- 
justed by the action of the regulator in conjunction with 



MODERN TYPES OP OIL ENGINES 367 

a pilot valve which is operated by the pressure from one 
of the stages of the air compressor. 

Ques. 850. — What type of governor is employed to 
effect the above mentioned regulation ? 

Ans. — A centrifugal governor, usually of the fly wheel 
design. 

Ques. 851. — Give a brief description of the first two 
Diesel engines built by the United States Government. 

Ans. — These engines constitute the power plant of the 
fuel ship "Maumee." Each engine will develop 2,500 
horse power at 136 r. p. m. and is of the two-cycle, six 
cylinder, cross head type. The scavenging pumps are 
mounted on the outboard columns of the even numbered 
cylinders and are driven by links and beams from the 
main cross heads. Each scavenging pump is double act- 
ing and draws the air from both sides of the piston. Di- 
rectly under each scavenging compressor, and driven by 
the same cross head, are two water pumps. 

Ques. 852. — What are the functions of these pumps? 

Ans. — To supply fresh water for cooling the pistons, 
lubrication for the main crank pin, cross head and thrust 
block bearing ; salt water for cooling all the engine parts 
except the pistons ; also service for bilge and sanitary 
systems. 

Ques. 853. — Where are the high pressure air compres- 
sors located on these engines? 

Ans. — They are mounted on the outboard columns of 
the odd numbered cylinders, and are driven from the 
main cross head by links and beams. 



368 QUESTIONS AND ANSWERS 

Ques. 854. — Describe the construction of the bedplate 
and main bearings. 

Ans. — The bed plate consists of three cast iron sec- 
tions bolted together. Each section contains three main 
bearings consisting of a flat bottomed cast iron piece sup- 
ported in the bed plate saddle, a lower main bearing brass 
cored for water circulation capable of being rolled out of 
the saddle without removing the crank shaft; and a flat 
topped upper bearing brass. The binding cap is of forged 
steel, and the bearing brasses are lined with a white metal 
consisting of 80 per cent tin, 15 per cent antimony and 5 
per cent copper. 

Ques. 855. — What is the diameter of the crankshaft 
for the engines of the "Maumee?" 

Ans. — i$y 2 inches. It is made of special forgings 
having a tensile strength of 71,000 to 78,000 lbs. and an 
elongation of 18 to 20 per cent. The sections are bored 
hollow and drilled for the forced lubrication system. 

Ques. 856. — Describe the piston rod. 

Ans. — The piston rod is of forged steel and bored 
hollow for the passage of the fresh water to and from the 
working piston. 

Ques. 857. — Describe in brief the construction of the 
piston. 

Ans. — The piston is divided into two parts, the work- 
ing piston, which consists of a specially lined casting cored 
for water circulation and ribbed for strength ; and a lower 
iron casting which is bolted to the piston rod. The two 
sections are not bolted to each other, although both are 



MODERN TYPES OF OIL ENGINES 369 

secured to the rod. The working piston is dished on top 
and is machined with greater clearance at its top than at 
its bottom. It carries six cast iron snap rings varying in 
width from the top to the bottom, the upper rings being 
given more clearance than the lower ones on account of 
the greater heat. The lower part of the main piston 
merely serves as a guide and is fitted with two cast iron 
snap rings at the bottom. 

Ques. 858. — What is the function of these two snap 
rings ? 

Ans. — To prevent the escape of gas into the engine 
room. 

Ques. 859. — Describe the process of cooling the piston 
while the engine is running. 

Ans. — Fresh water coming up from the rod enters 
the central compartment of the piston, passes out toward 
the side through cored passages at the top and finally 
reaches the concentric space in the piston rod through 
four pipes set at 45 degrees, returning from the highest 
point of the water space, and thus insuring a flow of 
water along the hottest parts of the piston. 

Ques. 860. — What advantage does this system of cool- 
ing possess ? 

Ans. — The advantage of simplicity. 

Ques. 861. — What is the disadvantage in connection 
With it ? 

Ans. — The disadvantage of heating the water entering 
the piston by that just leaving the piston. 



370 QUESTIONS AND ANSWERS 

Ques. 862. — Describe the construction of the mail 
cylinder. 

Ans. — It is made up of two parts, a cast iron jackel 
carrying the exhaust belt and a plain cylindrical liner of 
special cast iron. The space between the cylinder jacket 
and the liner forms the water jacket for the salt cooling 
water. The top of the liner is securely held in place by 
the cylinder head, while the lower end is free to expand 
through the stuffing box in the bottom of the jacket which 
prevents salt water leakage. The surface of the liner 
passing through the tight fit at the exhaust belt has sev- 
eral shallow grooves for the purpose of collecting any 
slight water leakage. These grooves are about 34 mcn 
in depth, by )A inch in width, and are connected to pet 
cocks on the outside of the jacket. These are kept open 
and serve as leak indicators. 

Ques. 863. — Describe the construction of the cylinder 
head. 

.Ans. — The cylinder head is secured to the cylinder 
by 12 studs. The joint between the head and liner is 
made tight by a thin copper gasket. The head has five 
openings to receive the valve cages. The center one is 
for the fuel valve, and the two largest openings on either 
side are for the scavenging valves ; the inboard opening 
is for the cylinder release valve, and the outboard open- 
ing is for the air starting valve. 

Ques. 864. — How is the cylinder head cooled ? 

Ans. — It is divided into two compartments for cool- 
ing. The water from the cylinder jacket is by-passed 



MODERN TYPES OF OIL ENGINES 371 

around the cylinder head joint into the lower compart- 
ment of the head through which it must all go before 
rising to the upper compartment. 

Ques. 865. — Describe the fuel spray valve and its 
operation. 

Ans. — This valve is located in the center of the head. 
It consists of a cast iron body, within which is housed a 
long forged steel needle valve that opens upward. This 
valve is opened by the cam shaft, and is ordinarily held 
shut by heavy springs. The compressed air for fuel in- 
jection is connected to the valve body at the top and 
maintains a constant pressure in the valve body, there 
being a safety valve in the air line at each cylinder. 

Ques. 866. — Where is the camshaft located? 

Ans. — It is located on the inboard side of the engine 
and is in four sections. The first section carries the cams 
for cylinders 1 and 2 ; the second the governor, the cam 
for cylinder No. 3 and an eccentric for driving the fuel 
pump for cylinders 1 and 2 ; the third carries the cam for 
cylinder No. 4 and the gear that transmits the motion of 
the vertical shaft to the cam shaft which is horizontal; 
and the fourth carries the cams for cylinders 5 and 6. 

Ques. 867. — Of what does the high pressure air sys- 
tem for one engine consist? 

Ans. — It consists of three attached air compressors, 
the spray flask of about 5 cubic feet capacity, the six start- 
ing-air flasks with a capacity of about 180 cubic feet, air 
separators, piping and release valves. There is also one 
auxiliary air compressor independently driven by steam, 



372 QUESTIONS AND ANSWERS 

with a capacity equal to that of one of the attached 
compressors. 

Ques. 868.— What is the function of the auxiliary a 
compressor ? 

Ans.— To provide air for charging the spray and stai 
ing flasks when all the other air is gone. 

Ques. 869.— Of what does the salt water cooling sy 
tern consist? 

Ans.— Two attached plunger pumps under the middl 
scavenger pump and an independently driven steam plut 
ger pump, together with the necessary piping and connec 
tion. Both attached pumps have a common suction, am 
each is of sufficient capacity to supply the salt wate 
system at normal power. 

Ques. 870.— Describe the course taken by the sal 
water used for cooling. 

Ans.— It is discharged by the pumps into a large mail 
at the back of the engine beneath the floor plate. From 
this main a branch leads upward to the bottom of each 
intercooler for the high pressure air compressors and to 
the bottom of each cooler in the scavenger pump cast- 
ings. The main then continues around the forward end 
of the engine, where a branch leads upward on the out- 
board side of the main bearing cap. Continuing around 
to the inboard side of the engine under the floor plate, 
the main supplies a branch to the bottom of each ahead 
crosshead guide. A collecting main runs around the en- 
gine at the height of the cylinder base. On the inboard 
side it receives the return cooling water from the main 



MODERN TYPES OF OIL ENGINES 373 

bearing and thrust block. On the outboard side of the 
engine it receives the cooling water from the scavenger 
cooler. 

Ques. 871. — Describe the further course of the cool- 
ing water at the back of the engine. 

Ans. — Back of the engine all the water in the collect- 
ing main enters the bottom of the main cylinder jackets, 
two' branches leading to each jacket. The cooling water 
leaving the high pressure inter-coolers of each compressor, 
is carried to the lower end of the jacket of the middle 
stage air compressor cylinder, from whence it is forced 
upward into the jacket of the low stage cylinder through 
two ferrules set partly into each cylinder at the joint. 
From the low stage jacket, the water enters the high stage 
jacket through two by-passes around the cylinder joint, 
and from the high stage jacket the water is forced into 
the high stage cylinder head through two by-passes 
around the joint between the head and cylinder. From 
the head of each high stage cylinder the water is led into 
the exhaust pipe jacket and from here is finally discharged 
into an overboard discharge main. 

Ques. 872. — How is the fresh cooling water carried 
to the piston ? 

Ans. — Fresh cooling water is drawn from a compart- 
ment in the double bottom, where it is cooled, to the piston 
through a swivel joint on the after beam bearing, a pipe 
secured to the beam, another swivel joint on the cross- 
head end of the beam, the main crosshead, a nickle-steel 
pipe running up through the center of the piston rod, and 



374 QUESTIONS AND ANSWERS 

four collecting pipes reaching the highest part of th| 
outer cooling space in the piston, and from thence retun 
ing through the concentric space in the piston rod, 
finally reaches a discharge main back of the engine vil 
links and beams and the forward end of the crosshead 11 
a manner similar to that by which it entered. 

Ques. 873. — Describe the facilities for maneuverinj 
the engine. 

Ans. — On the operator's platform is the maneuverinj 
control wheel, which controls the starting, stopping anc 
reversal of the engine by means of compressed air. Thu 
wheel also cuts off the fuel and spray air from the cylin 
ders during maneuvering and until the engine is turning 
over in the desired direction. Above the maneuvering 
control is a dial on which a pointer indicates the running 
position of the engine. There is also a hand cutout by 
which the engine can be instantly stopped. It operates to 
raise the suction valves of the fuel pumps thus rendering 
them inoperative. 

Ques. 874. — What other facilities are provided for 
hand control? 

Ans. — A fuel control wheel by means of which the 
quantity of fuel pumped into each cylinder may be con- 
trolled. A dial and pointer above the fuel control indi- 
cate in eight equal steps the quantity of fuel pumped, 
from a minimum to the maximum. Coming out from the 
shaft of the fuel control wheel is the needle stroke con 
trol which varies the stroke of the fuel spray needle from 
maximum to minimum. There is also a hand control f*»r 



MODERN TYPES OP OIL ENGINES 375 

the high pressure a i r which regulates the opening of the 
suctions of the low stage cylinders of the air compres- 
sors. The quantity and pressure of the spray air is thus 
controlled. 

Ques. 875. — What kind of oil is used in engines of 
the Diesel type ? 

Ans. — Crude petroleum having a heat value of 18,000 
to 20,000 b. t. u. per pound. 

Ques. 876. — How does fuel oil compare with coal in 
heat value ? 

Ans. — To compare the fuel consumption per brake 
horse power of an oil engine with that of a steam engine 
one pound of oil may be considered as equivalent to ij4 
lbs. of coal. 

Ques. 877. — What is the usual rate of fuel oil con- 
sumption per brake horse-power-hour for oil engines? 

Ans. — Recent tests of a 500 horse power engine of 
the Diesel type show an average oil consumption of 0.483 
lbs. of oil per brake horse-power-hour. 

Ques. 878. — Did the load on the engine vary to any 
extent during the course of these tests ? 

Ans. — It varied from 25 per cent below, to 113 per 
cent above normal rating. 

Ques. 879. — Regarding efficiency, what can be said 
of the Diesel type oil engine? 

Ans. — It gives a high efficiency in service, in fact is 
said to be one of the most efficient prime movers known 
at present (1917). 



376 QUESTIONS xVND ANSWERS 

Ques. 880. — Is auxiliary ignition apparatus required 
in the Diesel engine? 

Ans. — It is not. The fuel oil is ignited by the tem- 
perature of compression. This fuel does not explode as 
in a gasoline engine, but burns in the cylinder, and by 
the heating and expansion of the air and gases within 
the cylinder, the piston is forced out on its working stroke. 

Ques. 881. — What other type of oil engine resembles 
the Diesel engine in the process of ignition? 

Ans. — The Hornsby-Ackroyd Engine. In this engine 
the oil is first introduced into a vaporizer located at the 
back or side of the cylinder, the heat necessary for vapor- 
ization being supplied at starting by external lamps, but 
when the engine is in operation the continued combustion 
of the fuel supplies sufficient heat for both vaporization 
and ignition. 

Ques. 882. — How is the air necessary for combustion 
introduced into the cylinder? 

Ans. — This being a four-cycle engine, air enters the 
cylinder during the suction period of the cycle. Thus the 
cylinder becomes charged with air, and the vaporizer 
becomes filled with a spray of oil simultaneously. Dur- 
ing the compression period the air in the cylinder, being 
forced into the vaporizer, becomes properly mixed with 
the oil and an explosive mixture is formed. 

Ques. 883. — How is the oil fuel supplied to the 
Hornsby-Ackroyd engine ? 

Ans. — By an oil pump, the stroke of which is under 



MODERN TYPES OP OIL ENGINES 377 

control of the governor, thus giving close regulation of 
speed. This engine is built either horizontal or vertical. 

Ques. 884. — Describe some of the peculiar features of 
the Remington Oil Engine. 

Ans. — This engine is valveless, the gases being moved 
into and out of the cylinder through ports uncovered by 
the movement of piston, which itself also performs the 
function of a pump. 

Ques. 885. — How does this action take place? 

Ans. — The engine is of the vertical type, operating 
on the two-stroke cycle. On the up-stroke of the piston 
a partial vacuum is created in the enclosed crankcase, and 
when the bottom of the piston uncovers the inlet port 
which is directly under the exhaust port, the air rushes 
in and fills the crankcase at atmospheric pressure. On 
the next down stroke this air is compressed in the crank 
case to four or five pounds pressure ; while at the same 
time the mixture of oil-vapor and air already in the cylin- 
der is burning and expanding, thus forcing the piston 
down on its working stroke. When the piston approaches 
the end of its down stroke it uncovers the exhaust port 
on the side of the cylinder, permitting the burnt charge 
to escape to the atmosphere. Immediately after this event 
takes place the transfer port on the opposite side of the 
cylinder is uncovered by the piston, thus allowing a por- 
tion of the air compressed in the crank case to pass into 
the cylinder, where it is deflected upwards by the shape of 
the piston, and caused to fill the cylinder, thereby expell- 
ing the remainder of the burnt charge. The piston now 



378 QUESTIONS AND ANSWERS 

starts on another up-stroke, compressing the fresh charg 
of air into the hot cylinder head. 

Ques. 886. — How is the fuel oil admitted to th 
cylinder ? 

Ans. — When the piston is near the end of the upwan 
compression stroke, an oil pump mounted on the crank 
case and controlled by the governor injects the prope 
amount of oil through the nozzle into the space above th 
piston now occupied by the compressed and heated aii 
This oil is atomized in a vertical direction through ai 
opening near the end of the nozzle, and is thus vaporizec 
and gasified before it reaches the cylinder walls. 

Ques. 887. — How is ignition effected in the Remingtoi 
oil engine? 

Ans. — By means of a nickel steel plug located in th< 
center of the cylinder head, and kept red hot by the ex- 
plosions. By the burning of the oil spray in the com- 
pressed air the pressure is increased and the piston i: 
now forced downward on its power stroke. 

Ques. 888. — Of what type is the Remington oil en- 
gine? 

Ans. — It is a two-cycle engine, since the operations 
hitherto described take place with every revolution of th 
crank shaft. Therefore each down stroke is a power 
stroke. 

Several sizes of this engine are built especially to 
operate on semi-refined fuels, such as distillate, solar oil, 
gas oil, etc. All sizes of Remington oil engines are built 
to operate on all grades of ordinary kerosene oil. 



MODERN TYPES OF OIL ENGINES 379 

Ques. 889. — Does the use of kerosene and other distil- 
ates of petroleum as fuel for internal combustion engines 
five satisfactory results? 

Ans. — It does, provided the engine has been designed 
for using that grade of fuels. 

Ques. 890. — What are the principal characteristics of 
the Nordberg high compression oil engine? 

Ans. — This engine ignites its fuel of its own compres- 
ion. It therefore requires no hot bulb, torch, or other 
auxiliary ignition device. It has no valve gear or valves 
subject to the working pressure and heat, there being but 
one valve on the engine and it is located at a point where 
it is not affected by the heat. It operates its own fuel 
pump by means of an eccentric on the crank shaft. 

Ques. 891. — Of what type is the Nordberg engine? 

Ans. — It is of the two-cycle type. 

Ques. 892. — Describe the operations of the exhaust, 
and the admission of the scavenging air to the cylinder. 

Ans. — Near the end of the working stroke the piston 
uncovers the exhaust ports, and after these have been 
opened a certain amount, the scavenging port is also un- 
overed by the piston and fresh air from the scavenging 
space is blown into the cylinder and through the exhaust 
openings, thus cleaning out the burned gases and provid- 
ing fresh air for the next cycle. 

Ques. 893. — Describe the processes of compression 
md ignition in this engine. 

Ans. — With the piston on the return stroke, the air 
entrapped in the cylinder is compressed to a pressure of 



-* 



380 QUESTIONS AND ANSWERS 

approximately 450 pounds, and at the end of the strol 
fuel oil is injected through the fuel nozzle located in t 
cylinder head, and ignition occurs, due to the heat 
the compressed air. 

Ques 894. — How is this fuel supplied to the noz; 
under the required pressure? 

Ans. — By the fuel pump driven by an eccentric on t 
crank shaft. 

Ques. 895. — How is the quantity of fuel oil requir 
by the engine controlled in order to maintain a unifoi 
speed at varying loads ? 

Ans. — By means of a centrifugal shaft governor whi 
acts on the fuel pump through a rod, and determines t 
amount of oil which is by-passed by the pump, that 
the amount not used. 

Ques. 896. — Describe the construction of the fu 
pump and appurtenances. 

Ans. — This oil pump is a simple plunger pump, of 
very strong construction. The plunger receives its m< 
tion from a driving cam operated by an eccentric on t 
crank shaft. The plunger has a constant stroke, and t 
capacity of the pump is for a much greater quantity 
oil than the engine would ever use, but as before state< 
the amount of oil actually pumped to the fuel nozzle 
always under the control of the shaft governor. The fu 
pump and driving cam are located in a cast iron box ke] 
filled with oil, so that the pump operating mechanism 
continually submerged in this oil. 



MODERN TYPES OF OIL ENGINES 381 

Ques. 897. — How is the Nordberg oil engine started ? 

Ans. — By means of compressed air at a pressure of 
250 pounds admitted to the cylinder, behind the piston. 

Ques. 898. — Describe the starting valve, and its opera- 
;ion. 

Ans. — The starting valve is of the quick opening type, 
ind is manipulated by the operator who gives the cylinder 
;he proper charge of compressed air for the right portion 
)f the stroke. After one or two revolutions the operator 
starts the fuel pump by means of a lever which throws 
he pump cam into connection, thus starting the flow of 
fuel oil to the cylinder. The engine usually fires on the 
hird or fourth revolution. 

Ques. 899. — How is compressed air at 250 pounds 
Dressure supplied to the engine for starting? 

Ans. — From a welded steel storage tank kept charged 
kr means of a two-stage air compressor furnished with 
the engine. This air compressor is designed for a work- 
ng pressure of 250 pounds, and is provided with an inter- 
:ooler. It may be driven by a belt from the engine, or 
from a motor or line shaft. 

Ques. 900. — Does this compressor run continuously? 

Ans. — It does not. It is used only for short periods 
when recharging the air-storage tank after the oil engine 
las been put in operation. 

Ques. 901. — How is the scavenging air supplied to the 
cylinder? 

Ans. — The space between the piston and the front end 
of the cylinder is used as a compression space. On the 



. 



382 QUESTIONS AND ANSWERS 

back stroke of the piston, air is drawn into this spa 
through a piston valve driven by an eccentric on the mi 
crank shaft. On the forward stroke of the piston this i 
is slightly compressed in the space between cylinder he 
and piston, until at the end of the stroke, the scavengi 
port is opened by the piston, as already described. 

Ques. 902. — Describe the action of the fuel nozzle. 

Ans. — The fuel nozzle atomizes the fuel oil by din 
mechanical pressure from the fuel pump ; and not 
means of highly compressed air. 

Ques. 903. — What types of fuel oil can be used 
the Nordberg oil engine? 

Ans. — The leading types, such as regular fuel o 
kerosene, and other distillate. 

Ques. 904. — Describe the method of providing t 
required storage for this fuel. 

Ans. — A reservoir fitted with compartments for t 
different types of fuel oil is provided. This reservoir 
kept supplied with fuel oil by means of a small pum 
driven from the engine. This pump lifts the fuel oil froi 
the underground storage tank, and delivers it into th 
reservoir which stands at a level sufficiently high to allo^ 
the fuel oil to run by gravity to the fuel pump on the en 
gine. The overflow from this fuel reservoir can be pipe 
back to the underground tank. 

Ques. 905. — At what times is kerosene or distillat 
used as fuel on this engine? 

Ans. — Usually in starting, when the regular fuel oi 
is heavy or viscous. 



^ 



MODERN TYPES OF OIL ENGINES 383 

Ques. 906. — What changes are required in order to 
change from distillate to the regular fuel, or vice versa? 

Ans. — It is necessary only to turn a three-way cock. 

Ques. 907. — How is the cylinder cooled? 

Ans. — It is water jacketed, and the jacket spaces are 
provided with hand-holes for cleaning. 

Ques. 908. — What quantity of water is required for 
cooling? 

Ans. — From four to seven gallons per brake horse 
power hour, depending upon the temperature of the 
water. 

Ques. 909. — Is the Nordberg oil engine equipped with 
a cross-head? 

Ans. — It is provided with a cross-head running in 
bored guides. 

Ques. 910. — Of what type is the Lawson kerosene 
engine ? 

Ans. — It is of the vertical, four-cylinder type ; de- 
signed primarily to operate on kerosene, although it may 
be operated on power distillate, or gasoline. 

Ques. 911. — How is the fuel for this engine admitted 
to the cylinders? 

Ans. — By means of inlet poppet valves, located in the 
cylinder heads. These valves are operated by overhead 
tappets which receive their motion from a cam-shaft. 

Ques. 912. — How are the products of combustion ex- 
hausted from the cylinders? 

Ans. — By means of exhaust valves also located in the 
cylinder heads, and operated by the same cam-shaft. 



384 QUESTIONS AND ANSWERS 

Ques. 913. — Describe the fuel feeding device in v 
on the Lawson kerosene engine. 

Ans. — It is of the venturi atomizer type, the functi 
of which is to maintain a uniformly high velocity of 
through a venturi tube having radial holes in its restrict 
portion through which the fuel is admitted by suction. 

Ques. 914. — How is the speed of this engine cc 
trolled:* 

Ans. — By means of a fly-ball governor, driven from 
bevel gear on the cam-shaft, and acting to control the a 
mission of fuel to the cylinder. The governor acts 
rectly upon a two-ported barrel valve whose ports coinci 
with the ports in the valve housing when the engine is 
rest. When the engine has attained full speed the ban 
valve is rotated by the governor, thereby closing the low 
port and decreasing the amount of fuel and air admitt 
into the cylinder. At the same time the upper port 
also closed, deflecting more air through the nozzle a: 
maintaining practically a constant velocity of air at t 
point. 

Ques. 915. — How is adjustment made for no load ai 
full load? 

Ans. — By means of a fuel needle valve, in conjun 
tion with a butterfly valve in the air inlet. 

Ques. 916. — Is each cylinder equipped with a fu 
feeding device such as described? 

Ans. — A separate carburetor, or atomizer as it 
called, is provided for each cylinder, in order to prevei 
liquefying of the fuel before it reaches the cylinder. 



MODERN TYPES OF OIL ENGINES 385 

Ques. 917. — What provision is made to prevent pre- 
mature ignition on full load? 

Ans. — A water feed is provided for this purpose. 

Ques. 918. — Describe the cooling system in use on 
the Lawson engine. 

Ans. — The cylinders and cylinder heads are water 
jacketed. The heads carry the valves which seat directly 
against the water jacket, thereby bringing the water as 
close as possible to the valve heads, and thus prevent 
undue heating of the same, which is exceedingly detri- 
mental in a kerosene engine. 

Ques. 919. — What kind of piston is in use on this 
engine ? 

Ans. — The pistons are of the barrel or trunk type, 
each piston being equipped with four rings, three on its 
extreme upper end, and one on its extreme lower end. 

Ques. 920. — Describe the valve operating mechanism. 

Ans. — The cam-shaft is carried in five bronze bear- 
ings within the crank-case. The cams for each cylinder, 
viz., exhaust, inlet and igniter, are integral, and keyed 
to the cam-shaft. The push-rods acting upon the valve 
tappets are provided with hardened slides which are fitted 
with rollers for contact with the cams. The tappet 
levers are adjustable for wear. 

Ques. 921. — How is cooling water supplied to the 
Lawson kerosene engine? 

Ans. — By means of a circulating pump mounted on 
the engine, and driven directly from the crank-shaft 
through the medium of a chain and sprocket gear. 



386 QUESTIONS AND ANSWERS 

Ques. 922. — Describe the course of the water in its 
circulation through the jacket? 

Ans. — Water is admitted to the cylinder jacket on 
one side, directly in line with the lower line of the com- 
pression chamber, the cooling water not passing directly 
through the lower portion of the jacket, owing to the 
fact that the exhaust water is taken out of the top of 
the head by means of a polished brass manifold which 
is provided with expansion joints to avoid cracking. 

Ques. 923. — What system of ignition is used on this 
engine ? 

Ans. — The ignition is of the standard make and break 
type, and is arranged with two timing adjustments, one 
individual, and one simultaneous. The latter adjust- 
ment is used in starting, and is so arranged that all 
igniters may be stopped by shifting the timing lever. 
Directly over the igniter is mounted an insulated brass 
bar which is charged with current from a gear-driven 
magneto, alternating current. The igniters are provided 
with a spring coming in contact with this brass bar, thus 
eliminating wiring connection. 

Ques. 924. — How is the engine started? 

Ans. — An air starter is used which admits air into 
each cylinder through an automatic air valve in the head. 
As soon as the engine fires, the pressure within the 
cylinder holds this valve in its seat, thereby preventing 
admission of air. The starter consists of a main body, 
having four radial air ports connected by piping to the 
different cylinders. These ports are covered, and un- 



MODERN TYPES OF OIL ENGINES 387 

covered by a rotary disc valve having one port. This 
disc is held on its seat by the pressure of the air and 
is free to rotate when the air is shut off. The starter 
is connected to the end of the cam-shaft by means of 
a flexibld coupling. To start the engine, all that is 
necessary is to turn it on the center and open the air 
cock, no shifting of cams and gears being required. 

Ques. 925. — What kind of fuel is used in starting? 

Ans. — Gasoline is used until the engine has attained 
full speed, when it may be turned over until it runs on 
kerosene. 

Ques. 926. — Of what type is the Fairbanks-Morse 
marine oil engine? 

Ans. — It is a two-stroke cycle engine, securing igni- 
tion from a moderate compression and localized heat. 

Ques. 927. — Where is the combustion chamber lo- 
cated ? 

Ans. — Entirely outside the cylinder. The fuel oil is 
injected into this chamber. 

Ques. 928. — Does any portion of the fuel oil enter 
the cylinder? 

Ans. — Not in the form of oil. 

Ques. 929. — What advantage is gained by this action ? 

Ans. — The lubrication of cylinder and piston is not 
impaired. 

Ques. 930. — Is the electric spark used for ignition 
in this engine? 

Ans. — No. The heat retained in the combustion cham- 
ber is sufficient to cause ignition. 



INDEX 



A 

PAGE 

Absolute pressure 286 

Absolute zero 288 

Adiabatic curve 290-303 

Admission — 

Instant of 188 

Air- 
Admission to furnace 85 

Advantage in heating 131 

Composition of 17 

Locks, object of 124-126 

Product of 18 

Volume required for combustion 17-19 

Air pump — 

Description of 225-226 

Dimensions of 218 

Types of 224-225 

Valves for 227 

Angular advance 191 

Apparatus — 

Condensing, for steam turbines 338 

Ash- 
Dry 144 

Ash ejector 127 

Ash pits — 

Closed 123 

B 

Blow-off- 
Surface 112 

Bottom 113 

Boilers — 

Bracing 66 

Back arch for horizontal tubular 82-83 



INDEX 

PAGE 

Connecting up 138-139 

Feed pump 97 

Heating surface 86-87 

Horsepower 86-87 

Leaks 135 

Marine 169 

Material 65 

Operation 128 

Rivets 66 

Seams, welded 76 

Steam space of 110 

Types of 25-64 

Washing out 134-136 

Boiler construction 65 

Boyles law 14, 290 

Braces 66 

Bucket speed 304 

Bursting pressure 77 

C 

Calorimeter 145 

Carbon 17 

Carbon, monoxide 21 

Clearance 302 

Piston 289 

Steam 289 

Coal — 

Composition of 22 

Consumption of 156 

Dry 145 

Heating value of one pound 24 

Method of ascertaining cost 154-155 

Moisture in 145 

Cocks — 

Asbestos packed 117 

Gauge 104 

Hydrometer 114 

Combustible — 

Weight of 145 

Combustion 17 



INDEX 

PAGE 

Rate of 20 

Compression 302 

Advantage of 189 

Instant of 188 

Meaning of 289 

Condensation 233-235 

Cylinder 293 

Condenser — 

Advantages in use of ' 214-215 

For steam turbines 338 

Jet 217 

Siphon 216 

Surface 213 

Corrosion 168 

Cause of 169 

Prevention of 170 

Curves — 

Adiabatic 290-30! 

Expansion 290 

Isothermal 290 

Cut-off- 
Adjustable 2& 

Fixed 29£ 

Instant of 18£ 

D 

Dampers — 

Funnel 117-111 

Dead-center 202-20* 

Diagram — 

Characteristics of 29( 

Details of 285-28( 

Method of taking 284-28^ 

Distillers 253-2^ 

Draught li 

Artificial 19-125 

Essentials for 15(] 

Forced 122-lfl 

Measuring 150-15! 

Natural 19, 191 



INDEX 

PAGE 

Systems 131-132 

Draught gauge 150 

Dry-pipe 112 

Dynamics 291 

Dynamos — 

For marine service 260-264 

E 

Eccentric — 

Description of 190 

Position 191-204 

Throw of 191 

Efficiency — 

Plant 292 

Steam 291 

Ejector — 

Ash , 127 

Engine — 

Automatic 294 

Classes of 173-178 

Four- valve 185 

Marine 192 

Variable cut-off 294 

Evaporation — 

Equivalent 152 

Factor of 153-154 

Of water 152 

Evaporation tests — 

Apparatus for 141 

Data for 148 

Duration of 148 

Method of conducting 141 

Objects of 140 

Preparing for 146-147 

Evaporators — 

For marine service 253-254 

Exhaust steam — 

Disposal of 337 

Expansion 13 

Advantages of 179 



INDEX 

PAGE 

Curve 290 

Joint 116 

Rate of 181 

Ratio of 288 

F 

Feed pumps 97 

Feed water — 

Average temperature of 145-146 

Heaters 247-248 

How supplied to boiler 139 

Stoppage of supply 140 

Fire cleaning 129 

Firing — 

Hand 130 

Fire-main 269 

Fire tools 128 

Foot pound 290 

Force 291 

Forced draught 122-124 

Friction — 

In steam turbines 341 

Fuels 167 

Funnel-stays 119 

Funnel cover • . 121-122 

Furnace — 

Corrugated 26- 78 

Petroleum 165 

Temperature of 21 

Fusible plug 106-107 

G 

Galvanic action 170 

Cause of 170 

Prevention of 171 

Gases — 

Escaping 146 

Gauge — 

Cock 104 

Steam 107-110 



INDEX 

Governor — page 

Adjustment of 209-210 

Curtis steam turbine - 321 

Dunlop's 250-253 

Inertia 204-205 

Isochronal 204-295 

Marine 250 

Object of 249 

Principle of '. 249 

Shaft 295 

Throttling 294 

Grate-bars — 

Dimensions of 84 

Types of 85-86 

Grate-surface 84-85 

Grease filters 249 

H 

Hand firing 130 

Disadvantages of 156 

Heat- 
Latent 15 

Loss of 131 

Mechanical equivalent of 16 

Radiation of 16 

Sensible 15 

Specific 14 

Transmission of 16 

Horsepower — 

Boiler 155 

Constant 289 

Engine 289 

Indicated 289 

Net 289 

Hot-well 228-229 

Hydrometer 115 

Hydrometer cock * 114 

I 
Indicator — 

Care of 282-283 

Construction of 272-273 



INDEX 

PAGE 

Diagram 276-277 

Principles of 271 

Injector — 

Principles of 101 

Isothermal curve 290 

j 

Jet condenser 217 

Jet speed 304 

L 

Lap 187 

Inside 188 

Outside 188 

Latent heat 15 

Lead 188 

Decreasing 203 

Equalizing 203 

Object of 189 

Lighting— 

In marine service 265-266 

Link — 

Block 195 

Curvature of 194 

Slip of 195 

Link-motion 192 

Locks — 

Air 124-126 

M 

Mean effective pressure 287-297 

Method of finding 299 

Mechanical stokers 157 

Types of 157-161 

Moisture — 

In coal 145-152 

In steam 145 

Momentum 291 

Motion- 
First law of 290 



INDEX 

o 

Oil — PAGE 

Composition of 24 

Engines 361 

Fuel 24 

Heating value of 24 

Ordinates 293 

Oxidation 169 

P 

Petroleum — 

Advantages in use of 166-167 

Analysis of 164 

Heating value of 165 

Method of inducting to furnace 166 

Objection to 167 

Piston — 

Balancing 202 

Piston clearance 289 

Piston displacement .« 289 

Piston speed 289 

Plaximeter 300-301 

Plates- 
Oxidation of 169 

Power — 

Definition 290 

Pressure — 

Absolute 286 

Absolute back 287 

Back 287 

Boiler 286 

Bursting 77 

Condenser 288 

Expansion of 13 

Gauge 286 

Initial 286 

Mean effective 287 

Safe working 77 

Terminal 286-287 

Pumps — 

Air 215 

Bilge 266-267 



INDEX 

PAGB 

Boiler feed 241 

Centrifugal 231 

Circulating 230 

Double acting 242-246 

Dry air 339 

Duplex 97 

Fire, marine 267-268 

For marine service 240 

Location of 241 

Petroleum 166 

R 

Ratio — 

Of cylinder volumes 179 

Receiver 179-180 

Reducing motion 280 

Reducing wheel 279 

Re-evaporation — 

Cylinder 293 

Refrigeration — 

Cold air system 255-258 

Carbonic acid system 259-260 

Release — 

Instant of 188 

Rivets — 

Material for 66 

Test for 66 

Riveted joints — 

Efficiency of 72-74 

Lloyd's rules for 75 

Rocker arm — 

Adjustment of 206 

Rules— 

For finding heating surface of various types of boilers. .87-89 

For finding heating surface of corrugated flues 90 

For finding area of lever safety valves 93 

For finding speed of pump 98 

For finding velocity of flow in discharge pipe 98-99 

For finding required size of feed pump 100-101 

For finding boiler horsepower 156 



INDEX 

PAGR 

For finding weight of condensing water 234-235 

Rules— 

For finding I. H. P 301 

For finding bursting pressure 77 

For finding safe working pressure 77 

S 

Safe working pressure 77 

Safety valve — 

Duty of 90 

Types of 91-92 

Scale 137 

Sea water 170 

Composition of 211 

Disadvantages in using 212 

Sensible heat 15 

Separator 1 16-118 

Siphon condenser 216 

Siren, steam 112-113 

Smoke and soot 21 

Specific heat 14 

Speed — 

Bucket 304 

Jet 304 

Piston 289 

Regulation in Curtis turbine 321 

Regulation in Hamilton-Holzworth turbine 335-336 

Steam 304 

Stays- 
Gusset 67 

Funnel 119 

Material for 67-68 

Stay bolts 71-72 

Steam 7 

Action of in engine cylinder 173 

Clearance 289 

Consumption per H. P. hour 292 

Dry 145 

Gauge 107 

Maximum theoretical duty of 291 

Moisture in 145 



INDEX 

PAGE 

Physical properties of 8-12 

Relative volume of 7 

Theoretical velocity of 305 

Volume of 7 

Wire drawn 288 

Steam efficiency 291 

Steam gauge 107-110 

Steam siren 112-113 

Steam speed 304 

Steam turbine — 

Action of steam in 304 

Advantage over reciprocating engine 305-306, 322-340 

Allis-Chalmers 342 

Curtis (descriptive) 314-321 

De Laval (descriptive) 306-314 

Friction in 341 

Hamilton-Holzworth 330-337 

Principles of 304 

Westinghouse-Parsons 323-330 

Stoke-hold — 

Closed 126-127 

Stokers — 

For marine service 164 

Fuel for. 164 

Mechanical 157 

Method of supplying coal to 163-164 

Underfeed 162-163 

Surface condenser — 

Advantages of 213 

Construction and action of 219 

Tubes of 221-288 

T 

Tables- 
Analysis of coal 23 

Areas and circumferences of circles 237-238 

Capacities and speed of De Laval turbines 314 

Diameters of rivets 73 

Factors of evaporation 155 

Lap and lead of Corliss valves 209 

Physical properties of saturated steam 8-12 



INDEX 

PAGE 

Proportion of triple riveted butt joints 7€ 

Specific heat of various substances 14-15 

Water required for jet condensers 235 

Weight of water at various temperatures 144 

Tests- 
Evaporation 140 

For efficiency of boiler 149-152 

Test piece 65-66 

Thermal unit 16 

Thermo-dynamics 15 

Thermometer — 

Hot water 146 

Tubes- 
Cleaning 133-137 

Fire 25 

Galloway 37 

Material for 66 

Submerged 25 

Water 25 

Working test for 66 

Turbines — 

Action of steam in 304 

Advantage over reciprocating engine 305-306, 322-340 

Allis-Chalmers 342 

Curtis (descriptive) 306-314 

De Laval (descriptive) 314-321 

Friction in 341 

Hamilton-Holzworth 330-337 

Principles of 304 

Westinghouse-Parsons 323-330 

V 

Vacuum — 

How measured 213 

How maintained 215-219 

In turbine condensers 340 

Meaning of 213 

Perfect 287 

Vacuum gauge — 

Mercurial 214 

Spring 214 



INDEX 

Valves— page 

Check 104 

Double-ported 199 

Piston 202 

Poppet 199 

Treble-ported 200 

Safety 90 

Setting 202-205 

Sea 239 

Slide 186-187 

Steam stop 110 

Steam stop, automatic Ill 

Valve gear — 

Joy 196 

Marshall 195 

Reversing 194-195 

Valve-setting 202-205 

Defects in 297 

W 

Water- 
Evaporation per pound of coal 152 

Sea 170-211 

Quantity required for condenser 233 

Water column 105-106 

Whistle- 
Steam 111-112 

Wire drawing 288-297 

Wood- 
Composition of 24 

Disadvantage of as fuel 24 

Heating value of, in thermal units 24 

Work- 
Definition of 291 

Unit of 290 

Wrist-plate — 

Vibration of 207 

Z 

Zero- 
Absolute 288 

Zinc slabs 171-1T2 



